diff --git a/_episodes/03-create.md b/_episodes/03-create.md
index 4de62fd..b7412ff 100644
--- a/_episodes/03-create.md
+++ b/_episodes/03-create.md
@@ -65,7 +65,7 @@ If you are using a different version of git than I am, then then the exact
 wording of the output might be slightly different.
 
 ~~~
-# On branch master
+# On branch main
 #
 # Initial commit
 #
diff --git a/_episodes/04-changes.md b/_episodes/04-changes.md
index d4ec19d..319c17d 100644
--- a/_episodes/04-changes.md
+++ b/_episodes/04-changes.md
@@ -81,7 +81,7 @@ $ git status
 {: .bash}
 
 ~~~
-On branch master
+On branch main
 
 Initial commit
 
@@ -111,7 +111,7 @@ $ git status
 {: .bash}
 
 ~~~
-On branch master
+On branch main
 
 Initial commit
 
@@ -134,7 +134,7 @@ $ git commit -m "Start notes on the patient inflammation project"
 {: .bash}
 
 ~~~
-[[master (root-commit) 40b8a94] Start notes on the patient inflammation project
+[[main (root-commit) 40b8a94] Start notes on the patient inflammation project
  1 file changed, 1 insertion(+)
  create mode 100644 project.txt
 
@@ -166,7 +166,7 @@ $ git status
 {: .bash}
 
 ~~~
-On branch master
+On branch main
 nothing to commit, working tree clean
 
 ~~~
@@ -182,7 +182,7 @@ $ git log
 {: .bash}
 
 ~~~
-commit 40b8a9400329ed7324116cc9392dc8e4842d8501 (HEAD -> master)
+commit 40b8a9400329ed7324116cc9392dc8e4842d8501 (HEAD -> main)
 Author: Jane Smith <jane.smith@university.ac.uk>
 Date:   Wed Jan 3 10:34:07 2018 +0000
 
@@ -235,7 +235,7 @@ $ git status
 {: .bash}
 
 ~~~
-On branch master
+On branch main
 Changes not staged for commit:
   (use "git add <file>..." to update what will be committed)
   (use "git checkout -- <file>..." to discard changes in working directory)
@@ -299,7 +299,7 @@ $ git status
 {: .bash}
 
 ~~~
-On branch master
+On branch main
 Changes not staged for commit:
   (use "git add <file>..." to update what will be committed)
   (use "git checkout -- <file>..." to discard changes in working directory)
@@ -321,7 +321,7 @@ $ git commit -m "Add note about project responsibilities"
 {: .bash}
 
 ~~~
-[master 71ed26a] Add note about project responsibilities
+[main 71ed26a] Add note about project responsibilities
  1 file changed, 2 insertions(+)
 
 ~~~
@@ -452,7 +452,7 @@ $ git commit -m "Add note about extra team members"
 {: .bash}
 
 ~~~
-[master 005937f] Add note about extra team members
+[main 005937f] Add note about extra team members
  1 file changed, 1 insertion(+)
 ~~~
 {: .output}
@@ -465,7 +465,7 @@ $ git status
 {: .bash}
 
 ~~~
-On branch master
+On branch main
 nothing to commit, working directory clean
 ~~~
 {: .output}
@@ -478,7 +478,7 @@ $ git log
 {: .bash}
 
 ~~~
-commit 63f6bc6039c12ce897cf3f02bda1e95fd30fef58 (HEAD -> master)
+commit 63f6bc6039c12ce897cf3f02bda1e95fd30fef58 (HEAD -> main)
 Author: Jane Smith <jane.smith@university.ac.uk>
 Date:   Wed Jan 3 10:42:09 2018 +0000
 
@@ -532,7 +532,7 @@ Date:   Wed Jan 3 10:34:07 2018 +0000
 > {: .bash}
 >
 > ~~~
-> commit 63f6bc6039c12ce897cf3f02bda1e95fd30fef58 (HEAD -> master)
+> commit 63f6bc6039c12ce897cf3f02bda1e95fd30fef58 (HEAD -> main)
 > Author: Jane Smith <jane.smith@university.ac.uk>
 > Date:   Wed Jan 3 10:42:09 2018 +0000
 >
@@ -548,7 +548,7 @@ Date:   Wed Jan 3 10:34:07 2018 +0000
 > ~~~
 > {: .bash}
 > ~~~
-> 63f6bc6 (HEAD -> master) Add note about extra team members
+> 63f6bc6 (HEAD -> main) Add note about extra team members
 > 71ed26a Add note about project responsibilities
 > 40b8a94 Start notes on the patient inflammation project
 > ~~~
@@ -562,7 +562,7 @@ Date:   Wed Jan 3 10:34:07 2018 +0000
 > ~~~
 > {: .bash}
 > ~~~
-> * 63f6bc6 (HEAD -> master) Add note about extra team members
+> * 63f6bc6 (HEAD -> main) Add note about extra team members
 > * 71ed26a Add note about project responsibilities
 > * 40b8a94 Start notes on the patient inflammation project
 > ~~~
@@ -701,7 +701,7 @@ repository (`git commit`):
 > > ~~~
 > > {: .bash}
 > > ~~~
-> > [master a264d5c] Add note about what data would be useful
+> > [main a264d5c] Add note about what data would be useful
 > > 2 files changed, 3 insertions(+)
 > > create mode 100644 analysis.txt
 > > ~~~
@@ -741,7 +741,7 @@ repository (`git commit`):
 > > ~~~
 > > {: .bash}
 > > ~~~
-> > [master 4162a51] Update Jane's bio.
+> > [main 4162a51] Update Jane's bio.
 > > Author: Pete Jones <pete.jones@university.ac.uk>
 > > 1 file changed, 2 insertions(+), 2 deletions(-)
 > >
diff --git a/_episodes/05-history.md b/_episodes/05-history.md
index a17d541..f2d3aea 100644
--- a/_episodes/05-history.md
+++ b/_episodes/05-history.md
@@ -211,7 +211,7 @@ $ git status
 {: .bash}
 
 ~~~
-On branch master
+On branch main
 Changes not staged for commit:
   (use "git add <file>..." to update what will be committed)
   (use "git checkout -- <file>..." to discard changes in working directory)
@@ -271,7 +271,7 @@ $ git status
 {: .bash}
 
 ~~~
-# On branch master
+# On branch main
 Changes to be committed:
   (use "git reset HEAD <file>..." to unstage)
 # Changes not staged for commit:
@@ -305,7 +305,7 @@ $ git checkout HEAD project.txt
 > to revert `project.txt` to its state after the commit `f22b25e`.
 > If you forget `project.txt` in that command, Git will tell you that "You are in
 > 'detached HEAD' state." In this state, you shouldn't make any changes.
-> You can fix this by reattaching your head using ``git checkout master``
+> You can fix this by reattaching your head using ``git checkout main``
 {: .callout}
 
 It's important to remember that
diff --git a/_episodes/06-ignore.md b/_episodes/06-ignore.md
index 76b2810..b889399 100644
--- a/_episodes/06-ignore.md
+++ b/_episodes/06-ignore.md
@@ -30,7 +30,7 @@ $ git status
 {: .bash}
 
 ~~~
-On branch master
+On branch main
 Untracked files:
   (use "git add <file>..." to include in what will be committed)
 
@@ -75,7 +75,7 @@ $ git status
 {: .bash}
 
 ~~~
-On branch master
+On branch main
 Untracked files:
   (use "git add <file>..." to include in what will be committed)
 
@@ -98,7 +98,7 @@ $ git status
 {: .bash}
 
 ~~~
-# On branch master
+# On branch main
 nothing to commit, working directory clean
 ~~~
 {: .output}
@@ -128,7 +128,7 @@ $ git status --ignored
 {: .bash}
 
 ~~~
-On branch master
+On branch main
 Ignored files:
  (use "git add -f <file>..." to include in what will be committed)
 
diff --git a/_episodes/07-github.md b/_episodes/07-github.md
index b290f92..e22b428 100644
--- a/_episodes/07-github.md
+++ b/_episodes/07-github.md
@@ -24,7 +24,7 @@ on the web rather than on someone's laptop.
 
 Most programmers use hosting
 services like [GitHub](https://github.com), [BitBucket](https://bitbucket.org) or
-[GitLab](https://gitlab.com/) to hold those master copies; we'll explore the pros
+[GitLab](https://gitlab.com/) to hold those main copies; we'll explore the pros
 and cons of this in the final section of this lesson.
 
 Let's start by sharing the changes we've made to our current project with the
@@ -109,7 +109,7 @@ Once the nickname `origin` is set up, this command will push the changes from
 our local repository to the repository on GitHub:
 
 ~~~
-$ git push origin master
+$ git push origin main
 ~~~
 {: .bash}
 
@@ -121,7 +121,7 @@ Writing objects: 100% (16/16), 1.62 KiB | 1.62 MiB/s, done.
 Total 16 (delta 4), reused 0 (delta 0)
 remote: Resolving deltas: 100% (4/4), done.
 To https://github.com/ARCTraining/inflammation.git
- * [new branch]      master -> master
+ * [new branch]      main -> main
 ~~~
 {: .output}
 
@@ -180,19 +180,19 @@ Our local and remote repositories are now in this state:
 > option is synonymous with the `--set-upstream-to` option for the `git branch`
 > command, and is used to associate the current branch with a remote branch so
 > that the `git pull` command can be used without any arguments. To do this,
-> simply use `git push -u origin master` once the remote has been set up.
+> simply use `git push -u origin main` once the remote has been set up.
 {: .callout}
 
 We can pull changes from the remote repository to the local one as well:
 
 ~~~
-$ git pull origin master
+$ git pull origin main
 ~~~
 {: .bash}
 
 ~~~
 From https://github.com/ARCTraining/inflammation
- * branch            master     -> FETCH_HEAD
+ * branch            main     -> FETCH_HEAD
 Already up-to-date.
 
 ~~~
diff --git a/_episodes/08-collab.md b/_episodes/08-collab.md
index 1537cf5..99f8f40 100644
--- a/_episodes/08-collab.md
+++ b/_episodes/08-collab.md
@@ -69,7 +69,7 @@ $ git commit -m "First Python analysis script"
 {: .bash}
 
 ~~~
-[master 6cc98ec] First Python analysis script
+[main 6cc98ec] First Python analysis script
 1 file changed, 2 insertions(+)
 create mode 100644 code.py
 ~~~
@@ -78,7 +78,7 @@ create mode 100644 code.py
 Then push the change to the *Owner's repository* on GitHub:
 
 ~~~
-$ git push origin master
+$ git push origin main
 ~~~
 {: .bash}
 
@@ -89,7 +89,7 @@ Compressing objects: 100% (2/2), done.
 Writing objects: 100% (3/3), 354 bytes | 354.00 KiB/s, done.
 Total 3 (delta 0), reused 0 (delta 0)
 To https://github.com/jane/inflammation.git
-   9dba5e1..6cc98ec  master -> master
+   9dba5e1..6cc98ec  main -> main
 ~~~
 {: .output}
 
@@ -104,7 +104,7 @@ Collaborator.
 To download the Collaborator's changes from GitHub, the Owner now enters:
 
 ~~~
-$ git pull origin master
+$ git pull origin main
 ~~~
 {: .bash}
 
@@ -114,8 +114,8 @@ remote: Compressing objects: 100% (2/2), done.
 remote: Total 3 (delta 0), reused 3 (delta 0), pack-reused 0
 Unpacking objects: 100% (3/3), done.
 From https://github.com/ARCTraining/inflammation
- * branch            master     -> FETCH_HEAD
-   9dba5e1..6cc98ec  master     -> origin/master
+ * branch            main     -> FETCH_HEAD
+   9dba5e1..6cc98ec  main     -> origin/main
 Updating 9dba5e1..6cc98ec
 Fast-forward
  code.py | 2 ++
@@ -133,10 +133,10 @@ GitHub) are back in sync.
 > repository you are collaborating on, so you should `git pull` before making
 > our changes. The basic collaborative workflow would be:
 >
-> * update your local repo with `git pull origin master`,
+> * update your local repo with `git pull origin main`,
 > * make your changes and stage them with `git add`,
 > * commit your changes with `git commit -m`, and
-> * upload the changes to GitHub with `git push origin master`
+> * upload the changes to GitHub with `git push origin main`
 >
 > It is better to make many commits with smaller changes rather than
 > of one commit with massive changes: small commits are easier to
@@ -155,14 +155,14 @@ GitHub) are back in sync.
 > command line? And on GitHub?
 >
 > > ## Solution
-> > On the command line, the Collaborator can use ```git fetch origin master```
+> > On the command line, the Collaborator can use ```git fetch origin main```
 > > to get the remote changes into the local repository, but without merging
-> > them. Then by running ```git diff master origin/master``` the Collaborator
+> > them. Then by running ```git diff main origin/main``` the Collaborator
 > > will see the changes output in the terminal.
 > >
 > > On GitHub, the Collaborator can go to their own fork of the repository and
 > > look right above the light blue latest commit bar for a gray bar saying
-> > "This branch is 1 commit behind Our-Repository:master." On the far right of
+> > "This branch is 1 commit behind Our-Repository:main." On the far right of
 > > that gray bar is a Compare icon and link. On the Compare page the
 > > Collaborator should change the base fork to their own repository, then click
 > > the link in the paragraph above to "compare across forks", and finally
diff --git a/_episodes/09-conflict.md b/_episodes/09-conflict.md
index d9b57fd..17ab0cf 100644
--- a/_episodes/09-conflict.md
+++ b/_episodes/09-conflict.md
@@ -67,13 +67,13 @@ $ git commit -m "Add a line to the collaborator copy"
 {: .bash}
 
 ~~~
-[master f4915d6] Add a line to the collaborator copy
+[main f4915d6] Add a line to the collaborator copy
  1 file changed, 1 insertion(+)
 ~~~
 {: .output}
 
 ~~~
-$ git push origin master
+$ git push origin main
 ~~~
 {: .bash}
 
@@ -85,7 +85,7 @@ Writing objects: 100% (3/3), 333 bytes | 333.00 KiB/s, done.
 Total 3 (delta 2), reused 0 (delta 0)
 remote: Resolving deltas: 100% (2/2), completed with 2 local objects.
 To https://github.com/ARCTraining/inflammation.git
-   6cc98ec..f4915d6  master -> master
+   6cc98ec..f4915d6  main -> main
 ~~~
 {: .output}
 
@@ -119,7 +119,7 @@ $ git commit -m "Add a line in the originator's copy"
 {: .bash}
 
 ~~~
-[master ef10d89] Add a line in the originator's copy
+[main ef10d89] Add a line in the originator's copy
  1 file changed, 1 insertion(+)
 ~~~
 {: .output}
@@ -127,13 +127,13 @@ $ git commit -m "Add a line in the originator's copy"
 but Git won't let us push it to GitHub:
 
 ~~~
-$ git push origin master
+$ git push origin main
 ~~~
 {: .bash}
 
 ~~~
 To https://github.com/jane/inflammation.git
- ! [rejected]        master -> master (fetch first)
+ ! [rejected]        main -> main (fetch first)
 error: failed to push some refs to 'https://github.com/jane/inflammation.git'
 hint: Updates were rejected because the remote contains work that you do
 hint: not have locally. This is usually caused by another repository pushing
@@ -153,7 +153,7 @@ and then push that.
 Let's start by pulling:
 
 ~~~
-$ git pull origin master
+$ git pull origin main
 ~~~
 {: .bash}
 
@@ -163,8 +163,8 @@ remote: Compressing objects: 100% (1/1), done.
 remote: Total 3 (delta 2), reused 3 (delta 2), pack-reused 0
 Unpacking objects: 100% (3/3), done.
 From https://github.com/jane/inflammation
- * branch            master     -> FETCH_HEAD
-   6cc98ec..f4915d6  master     -> origin/master
+ * branch            main     -> FETCH_HEAD
+   6cc98ec..f4915d6  main     -> origin/main
 Auto-merging project.txt
 CONFLICT (content): Merge conflict in project.txt
 Automatic merge failed; fix conflicts and then commit the result.
@@ -236,7 +236,7 @@ $ git status
 {: .bash}
 
 ~~~
-On branch master
+On branch main
 All conflicts fixed but you are still merging.
   (use "git commit" to conclude merge)
 
@@ -253,14 +253,14 @@ $ git commit -m "Merge changes from GitHub"
 {: .bash}
 
 ~~~
-[master 2abf2b1] Merge changes from GitHub
+[main 2abf2b1] Merge changes from GitHub
 ~~~
 {: .output}
 
 Now we can push our changes to GitHub:
 
 ~~~
-$ git push origin master
+$ git push origin main
 ~~~
 {: .bash}
 
@@ -272,7 +272,7 @@ Writing objects: 100% (7/7), 755 bytes | 755.00 KiB/s, done.
 Total 7 (delta 4), reused 0 (delta 0)
 remote: Resolving deltas: 100% (4/4), completed with 3 local objects.
 To https://github.com/jane/inflammation.git
-   f4915d6..dc29981  master -> master
+   f4915d6..dc29981  main -> main
 ~~~
 {: .output}
 
@@ -281,7 +281,7 @@ so we don't have to fix things by hand again
 when the collaborator who made the first change pulls again:
 
 ~~~
-$ git pull origin master
+$ git pull origin main
 ~~~
 {: .bash}
 
@@ -291,8 +291,8 @@ remote: Compressing objects: 100% (3/3), done.
 remote: Total 7 (delta 4), reused 7 (delta 4), pack-reused 0
 Unpacking objects: 100% (7/7), done.
 From https://github.com/jane/inflammation
- * branch            master     -> FETCH_HEAD
-   f4915d6..dc29981  master     -> origin/master
+ * branch            main     -> FETCH_HEAD
+   f4915d6..dc29981  main     -> origin/main
 Updating f4915d6..dc29981
 Fast-forward
  analysis.txt | 1 +
@@ -327,7 +327,7 @@ correctly. If you find yourself resolving a lot of conflicts in a project,
 consider these technical approaches to reducing them:
 
 - Pull from upstream more frequently, especially before starting new work
-- Use topic branches to segregate work, merging to master when complete
+- Use topic branches to segregate work, merging to main when complete
 - Make smaller more atomic commits
 - Where logically appropriate, break large files into smaller ones so that it is
   less likely that two authors will alter the same file simultaneously
@@ -392,7 +392,7 @@ Conflicts can also be minimized with project management strategies:
 > > {: .bash}
 > >
 > > ~~~
-> > [master c769bc5] Add a chart image
+> > [main c769bc5] Add a chart image
 > > 1 file changed, 0 insertions(+), 0 deletions(-)
 > > create mode 100644 chart1.jpg
 > > ~~~
@@ -405,13 +405,13 @@ Conflicts can also be minimized with project management strategies:
 > > When Jane tries to push, she gets a familiar message:
 > >
 > > ~~~
-> > $ git push origin master
+> > $ git push origin main
 > > ~~~
 > > {: .bash}
 > >
 > > ~~~
 To https://github.com/jane/inflammation.git
- ! [rejected]        master -> master (fetch first)
+ ! [rejected]        main -> main (fetch first)
 error: failed to push some refs to 'https://github.com/jane/inflammation.git'
 hint: Updates were rejected because the remote contains work that you do
 hint: not have locally. This is usually caused by another repository pushing
@@ -424,7 +424,7 @@ hint: See the 'Note about fast-forwards' in 'git push --help' for details.
 > > We've learned that we must pull first and resolve any conflicts:
 > >
 > > ~~~
-> > $ git pull origin master
+> > $ git pull origin main
 > > ~~~
 > > {: .bash}
 > >
@@ -432,14 +432,14 @@ hint: See the 'Note about fast-forwards' in 'git push --help' for details.
 > > a message like this:
 > >
 > > ~~~
-> > $ git pull origin master
+> > $ git pull origin main
 > > remote: Counting objects: 3, done.
 > > remote: Compressing objects: 100% (3/3), done.
 > > remote: Total 3 (delta 0), reused 3 (delta 0), pack-reused 0
 > > Unpacking objects: 100% (3/3), done.
 > > From https://github.com/ARCTraining/inflammation
-> >  * branch            master     -> FETCH_HEAD
-> >   dc29981..c769bc5  master     -> origin/master
+> >  * branch            main     -> FETCH_HEAD
+> >   dc29981..c769bc5  main     -> origin/main
 > > warning: Cannot merge binary files: chart1.jpg (HEAD vs. c769bc59aa612198cf77ac01a9e8f8479d7940ea)
 > > Auto-merging chart1.jpg
 > > CONFLICT (add/add): Merge conflict in chart1.jpg
@@ -471,7 +471,7 @@ hint: See the 'Note about fast-forwards' in 'git push --help' for details.
 > > {: .bash}
 > >
 > > ~~~
-> > [master 860c242] Use the greyscale image instead of the colour one
+> > [main 860c242] Use the greyscale image instead of the colour one
 > > ~~~
 > > {: .output}
 > >
@@ -486,7 +486,7 @@ hint: See the 'Note about fast-forwards' in 'git push --help' for details.
 > > {: .bash}
 > >
 > > ~~~
-> > [master da21b34] Use the colour image instead of the greyscale one
+> > [main da21b34] Use the colour image instead of the greyscale one
 > > ~~~
 > > {: .output}
 > >
@@ -514,7 +514,7 @@ hint: See the 'Note about fast-forwards' in 'git push --help' for details.
 > > {: .bash}
 > >
 > > ~~~
-> >[master 6aa1183] Use two images: grey and colour
+> >[main 6aa1183] Use two images: grey and colour
 > > 2 files changed, 0 insertions(+), 0 deletions(-)
 > > create mode 100644 chart1-colour.jpg
 > > rename chart1.jpg => chart1-grey.jpg (100%)
@@ -558,11 +558,11 @@ hint: See the 'Note about fast-forwards' in 'git push --help' for details.
 > >
 > > |order|action . . . . . . |command . . . . . . . . . . . . . . . . . . . |
 > > |-----|-------------------|----------------------------------------------|
-> > |1    | Update local      | `git pull origin master`                     |
+> > |1    | Update local      | `git pull origin main`                     |
 > > |2    | Make changes      | `echo 100 >> numbers.txt`                    |
 > > |3    | Stage changes     | `git add numbers.txt`                        |
 > > |4    | Commit changes    | `git commit -m "Add 100 to numbers.txt"`     |
-> > |5    | Update remote     | `git push origin master`                     |
+> > |5    | Update remote     | `git push origin main`                     |
 > > |6    | Celebrate!        | `AFK`                                        |
 > >
 > {: .solution}
diff --git a/_episodes/14-supplemental-rstudio.md b/_episodes/14-supplemental-rstudio.md
index 99c4c6e..120f275 100644
--- a/_episodes/14-supplemental-rstudio.md
+++ b/_episodes/14-supplemental-rstudio.md
@@ -83,7 +83,7 @@ the history:
 > If this is the case, it generally means that RStudio doesn't know the
 > location of any other version of your repository (i.e. the one on GitHub).
 > To fix this, open a terminal to the repository and enter the command:
-> `git push -u origin master`. Then restart RStudio.
+> `git push -u origin main`. Then restart RStudio.
 {: .callout}
 
 If we click on "history", we can see a pretty graphical version of what
diff --git a/_extras/discuss.md b/_extras/discuss.md
index a2af29f..a7250fa 100644
--- a/_extras/discuss.md
+++ b/_extras/discuss.md
@@ -242,7 +242,7 @@ $ git status
 {: .bash}
 
 ~~~
-On branch master
+On branch main
 nothing to commit, working directory clean
 ~~~
 {: .output}
@@ -257,7 +257,7 @@ $ git status
 {: .bash}
 
 ~~~
-On branch master
+On branch main
 Changes to be committed:
    (use "git reset HEAD <file>..." to unstage)
 
@@ -299,7 +299,7 @@ $ git status
 {: .bash}
 
 ~~~
-On branch master
+On branch main
 Changes not staged for commit:
    (use "git add/rm <file>..." to update what will be committed)
    (use "git checkout -- <file>..." to discard changes in working directory)
@@ -322,7 +322,7 @@ $ git status
 {: .bash}
 
 ~~~
-On branch master
+On branch main
 Changes to be committed:
    (use "git reset HEAD <file>..." to unstage)
 
@@ -370,7 +370,7 @@ $ git status
 {: .bash}
 
 ~~~
-# On branch master
+# On branch main
 # Changes to be committed:
 #   (use "git reset HEAD <file>..." to unstage)
 #
@@ -409,7 +409,7 @@ $ git status
 {: .bash}
 
 ~~~
-On branch master
+On branch main
 Changes not staged for commit:
   (use "git add/rm <file>..." to update what will be committed)
   (use "git checkout -- <file>..." to discard changes in working directory)
@@ -437,7 +437,7 @@ $ git status
 {: .bash}
 
 ~~~
-On branch master
+On branch main
 Changes to be committed:
   (use "git reset HEAD <file>..." to unstage)
 
diff --git a/_extras/guide.md b/_extras/guide.md
index 22b88f5..6f42f1f 100644
--- a/_extras/guide.md
+++ b/_extras/guide.md
@@ -146,9 +146,9 @@ working in teams or not, because it is
     doing `$ git checkout f22b25e mars.txt`, someone does `$ git checkout
     f22b25e`, they wind up in the "detached HEAD" state and confusion abounds.
     It's then possible to keep on committing, but things like `git push origin
-    master` a bit later will not give easily comprehensible results.  It also
+    main` a bit later will not give easily comprehensible results.  It also
     makes it look like commits can be lost.  To "fix" a "detached HEAD", simply
-    `git checkout master`.
+    `git checkout main`.
 
 *   This is a good moment to show a log within a Git GUI. If you skip it
     because you're short on time, show it once in GitHub.