diff --git a/CHANGELOG.md b/CHANGELOG.md
index 41ad31a..3660793 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,12 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ## Unreleased
 
+## 0.12.0 - 2023-07-28
+
+### Added
+
+- Summary metric type (mostly for Prometheus adapter).
+
 ## 0.11.0 - 2021-09-25
 
 ### Added
diff --git a/README.md b/README.md
index a565254..1f73f64 100644
--- a/README.md
+++ b/README.md
@@ -43,6 +43,7 @@ And then execute:
           comment "How long whistles are being active"
           unit :seconds
         end
+        summary :bells_ringing_duration, unit: :seconds, comment: "How long bells are ringing"
       end
     end
     ```
@@ -181,7 +182,7 @@ Add the following to your `rails_helper.rb` (or `spec_helper.rb`):
 require "yabeda/rspec"
 ```
 
-Now you can use `increment_yabeda_counter`, `update_yabeda_gauge`, and `measure_yabeda_histogram` matchers:
+Now you can use `increment_yabeda_counter`, `update_yabeda_gauge`, `measure_yabeda_histogram`, and `observe_yabeda_summary` matchers:
 
 ```ruby
 it "increments counters" do
@@ -201,7 +202,7 @@ end
 
 Note that tags you specified doesn't need to be exact, but can be a subset of tags used on metric update. In this example updates with following sets of tags `{ method: "command", command: "subscribe", status: "SUCCESS" }` and `{ method: "command", command: "subscribe", status: "FAILURE" }` will make test example to pass.
 
-And check for values with `by` for counters, `to` for gauges, and `with` for gauges and histograms (and you [can use other matchers here](https://relishapp.com/rspec/rspec-expectations/v/3-10/docs/composing-matchers)):
+And check for values with `by` for counters, `to` for gauges, and `with` for histograms and summaries (and you [can use other matchers here](https://relishapp.com/rspec/rspec-expectations/v/3-10/docs/composing-matchers)):
 
 ```ruby
 expect { subject }.to \
diff --git a/lib/yabeda/base_adapter.rb b/lib/yabeda/base_adapter.rb
index 0e9f660..ac4ff0d 100644
--- a/lib/yabeda/base_adapter.rb
+++ b/lib/yabeda/base_adapter.rb
@@ -8,6 +8,7 @@ def register!(metric)
       when Counter   then register_counter!(metric)
       when Gauge     then register_gauge!(metric)
       when Histogram then register_histogram!(metric)
+      when Summary   then register_summary!(metric)
       else raise "#{metric.class} is unknown metric type"
       end
     end
@@ -36,6 +37,14 @@ def perform_histogram_measure!(_metric, _tags, _value)
       raise NotImplementedError, "#{self.class} doesn't support measuring histograms"
     end
 
+    def register_summary!(_metric)
+      raise NotImplementedError, "#{self.class} doesn't support summaries as metric type!"
+    end
+
+    def perform_summary_observe!(_metric, _tags, _value)
+      raise NotImplementedError, "#{self.class} doesn't support observing summaries"
+    end
+
     # Hook to enable debug mode in adapters when it is enabled in Yabeda itself
     def debug!; end
   end
diff --git a/lib/yabeda/dsl/class_methods.rb b/lib/yabeda/dsl/class_methods.rb
index c8dd70c..dc00ded 100644
--- a/lib/yabeda/dsl/class_methods.rb
+++ b/lib/yabeda/dsl/class_methods.rb
@@ -4,6 +4,7 @@
 require "yabeda/counter"
 require "yabeda/gauge"
 require "yabeda/histogram"
+require "yabeda/summary"
 require "yabeda/group"
 require "yabeda/global_group"
 require "yabeda/dsl/metric_builder"
@@ -55,6 +56,12 @@ def histogram(*args, **kwargs, &block)
         register_metric(metric)
       end
 
+      # Register a summary
+      def summary(*args, **kwargs, &block)
+        metric = MetricBuilder.new(Summary).build(args, kwargs, @group, &block)
+        register_metric(metric)
+      end
+
       # Add default tag for all metric
       #
       # @param name [Symbol] Name of default tag
diff --git a/lib/yabeda/rspec.rb b/lib/yabeda/rspec.rb
index fea9784..deed416 100644
--- a/lib/yabeda/rspec.rb
+++ b/lib/yabeda/rspec.rb
@@ -11,6 +11,7 @@ module RSpec
 require_relative "rspec/increment_yabeda_counter"
 require_relative "rspec/update_yabeda_gauge"
 require_relative "rspec/measure_yabeda_histogram"
+require_relative "rspec/observe_yabeda_summary"
 
 RSpec.configure do |config|
   config.before(:suite) do
diff --git a/lib/yabeda/rspec/observe_yabeda_summary.rb b/lib/yabeda/rspec/observe_yabeda_summary.rb
new file mode 100644
index 0000000..b50ae7d
--- /dev/null
+++ b/lib/yabeda/rspec/observe_yabeda_summary.rb
@@ -0,0 +1,80 @@
+# frozen_string_literal: true
+
+require_relative "base_matcher"
+
+module Yabeda
+  module RSpec
+    # Checks whether Yabeda summary was observed during test run or not
+    # @param metric [Yabeda::Summary,String,Symbol] metric instance or name
+    # @return [Yabeda::RSpec::ObserveYabedaSummary]
+    def observe_yabeda_summary(metric)
+      ObserveYabedaSummary.new(metric)
+    end
+
+    # Custom matcher class with implementation for +observe_yabeda_summary+
+    class ObserveYabedaSummary < BaseMatcher
+      def with(value)
+        @expected_value = value
+        self
+      end
+
+      attr_reader :expected_value
+
+      def initialize(*)
+        super
+        return if metric.is_a? Yabeda::Summary
+
+        raise ArgumentError, "Pass summary instance/name to `observe_yabeda_summary`. Got #{metric.inspect} instead"
+      end
+
+      def match(metric, block)
+        block.call
+
+        observations = filter_matching_changes(Yabeda::TestAdapter.instance.summaries.fetch(metric))
+
+        observations.values.any? { |observation| expected_value.nil? || values_match?(expected_value, observation) }
+      end
+
+      def match_when_negated(metric, block)
+        unless expected_value.nil?
+          raise NotImplementedError, <<~MSG
+            `expect {}.not_to observe_yabeda_summary` doesn't support specifying values with `.with`
+            as it can lead to false positives.
+          MSG
+        end
+
+        block.call
+
+        observations = filter_matching_changes(Yabeda::TestAdapter.instance.summaries.fetch(metric))
+
+        observations.none?
+      end
+
+      def failure_message
+        "expected #{expected_formatted} " \
+          "to be observed #{"with #{expected} " unless expected_value.nil?}" \
+          "#{"with tags #{::RSpec::Support::ObjectFormatter.format(tags)} " if tags}" \
+          "but #{actual_changes_message}"
+      end
+
+      def failure_message_when_negated
+        "expected #{expected_formatted} " \
+          "not to be observed " \
+          "#{"with tags #{::RSpec::Support::ObjectFormatter.format(tags)} " if tags}" \
+          "but #{actual_changes_message}"
+      end
+
+      def actual_changes_message
+        observations = Yabeda::TestAdapter.instance.summaries.fetch(metric)
+        if observations.empty?
+          "no observations of this summary have been made"
+        elsif tags && observations.key?(tags)
+          formatted_tags = ::RSpec::Support::ObjectFormatter.format(tags)
+          "has been observed with #{observations.fetch(tags)} with tags #{formatted_tags}"
+        else
+          "following observations have been made: #{::RSpec::Support::ObjectFormatter.format(observations)}"
+        end
+      end
+    end
+  end
+end
diff --git a/lib/yabeda/summary.rb b/lib/yabeda/summary.rb
new file mode 100644
index 0000000..4edd708
--- /dev/null
+++ b/lib/yabeda/summary.rb
@@ -0,0 +1,28 @@
+# frozen_string_literal: true
+
+module Yabeda
+  # Base class for complex metric for measuring time values that allow to
+  # calculate averages, percentiles, and so on.
+  class Summary < Metric
+    # rubocop: disable Metrics/MethodLength
+    def observe(tags, value = nil)
+      if value.nil? ^ block_given?
+        raise ArgumentError, "You must provide either numeric value or block for Yabeda::Summary#observe!"
+      end
+
+      if block_given?
+        starting = Process.clock_gettime(Process::CLOCK_MONOTONIC)
+        yield
+        value = (Process.clock_gettime(Process::CLOCK_MONOTONIC) - starting)
+      end
+
+      all_tags = ::Yabeda::Tags.build(tags, group)
+      values[all_tags] = value
+      ::Yabeda.adapters.each do |_, adapter|
+        adapter.perform_summary_observe!(self, all_tags, value)
+      end
+      value
+    end
+    # rubocop: enable Metrics/MethodLength
+  end
+end
diff --git a/lib/yabeda/test_adapter.rb b/lib/yabeda/test_adapter.rb
index 7131a66..e56743e 100644
--- a/lib/yabeda/test_adapter.rb
+++ b/lib/yabeda/test_adapter.rb
@@ -9,18 +9,21 @@ module Yabeda
   class TestAdapter < BaseAdapter
     include Singleton
 
-    attr_reader :counters, :gauges, :histograms
+    attr_reader :counters, :gauges, :histograms, :summaries
 
+    # rubocop:disable Metrics/AbcSize
     def initialize
       super
       @counters   = Hash.new { |ch, ck| ch[ck] = Hash.new { |th, tk| th[tk] = 0 } }
       @gauges     = Hash.new { |gh, gk| gh[gk] = Hash.new { |th, tk| th[tk] = nil } }
       @histograms = Hash.new { |hh, hk| hh[hk] = Hash.new { |th, tk| th[tk] = nil } }
+      @summaries  = Hash.new { |sh, sk| sh[sk] = Hash.new { |th, tk| th[tk] = nil } }
     end
+    # rubocop:enable Metrics/AbcSize
 
     # Call this method after every test example to quickly get blank state for the next test example
     def reset!
-      [@counters, @gauges, @histograms].each do |collection|
+      [@counters, @gauges, @histograms, @summaries].each do |collection|
         collection.each_value(&:clear) # Reset tag-values hash to be empty
       end
     end
@@ -37,6 +40,10 @@ def register_histogram!(metric)
       @histograms[metric]
     end
 
+    def register_summary!(metric)
+      @summaries[metric]
+    end
+
     def perform_counter_increment!(counter, tags, increment)
       @counters[counter][tags] += increment
     end
@@ -48,5 +55,9 @@ def perform_gauge_set!(gauge, tags, value)
     def perform_histogram_measure!(histogram, tags, value)
       @histograms[histogram][tags] = value
     end
+
+    def perform_summary_observe!(summary, tags, value)
+      @summaries[summary][tags] = value
+    end
   end
 end
diff --git a/lib/yabeda/version.rb b/lib/yabeda/version.rb
index 8922940..1d1e3b7 100644
--- a/lib/yabeda/version.rb
+++ b/lib/yabeda/version.rb
@@ -1,5 +1,5 @@
 # frozen_string_literal: true
 
 module Yabeda
-  VERSION = "0.11.0"
+  VERSION = "0.12.0"
 end
diff --git a/spec/yabeda/dsl/class_methods_spec.rb b/spec/yabeda/dsl/class_methods_spec.rb
index 1d9f965..3b2fe9c 100644
--- a/spec/yabeda/dsl/class_methods_spec.rb
+++ b/spec/yabeda/dsl/class_methods_spec.rb
@@ -96,6 +96,19 @@
     end
   end
 
+  describe ".summary" do
+    subject { Yabeda.test_summary }
+
+    context "when properly configured" do
+      before do
+        Yabeda.configure { summary(:test_summary) }
+        Yabeda.configure! unless Yabeda.already_configured?
+      end
+
+      it("defines method on root object") { is_expected.to be_a(Yabeda::Summary) }
+    end
+  end
+
   describe ".default_tag" do
     subject { Yabeda.default_tags }
 
diff --git a/spec/yabeda/rspec/observe_yabeda_summary_spec.rb b/spec/yabeda/rspec/observe_yabeda_summary_spec.rb
new file mode 100644
index 0000000..1230636
--- /dev/null
+++ b/spec/yabeda/rspec/observe_yabeda_summary_spec.rb
@@ -0,0 +1,141 @@
+# frozen_string_literal: true
+
+require "yabeda/rspec"
+
+RSpec.describe "Yabeda RSpec matchers" do
+  before do
+    Yabeda.reset!
+    Yabeda.configure do
+      summary :test_summary
+      summary :other_summary
+    end
+    Yabeda.register_adapter(:test, Yabeda::TestAdapter.instance)
+    Yabeda.configure!
+  end
+
+  describe "#observe_yabeda_summary" do
+    it "succeeds when given summary was updated by any value" do
+      expect do
+        Yabeda.test_summary.observe({}, 42)
+      end.to observe_yabeda_summary(Yabeda.test_summary)
+    end
+
+    it "fails when given summary wasn't updated" do
+      expect do
+        expect do
+          # nothing here
+        end.to observe_yabeda_summary(Yabeda.test_summary)
+      end.to raise_error(RSpec::Expectations::ExpectationNotMetError)
+    end
+
+    it "fails when any other summary was updated" do
+      expect do
+        expect do
+          Yabeda.other_summary.observe({}, 0.001)
+        end.to observe_yabeda_summary(Yabeda.test_summary)
+      end.to raise_error(RSpec::Expectations::ExpectationNotMetError)
+    end
+
+    context "with value specified" do
+      it "succeeds when given summary was updated by exact value" do
+        expect do
+          Yabeda.test_summary.observe({}, 42)
+        end.to observe_yabeda_summary(Yabeda.test_summary).with(42)
+      end
+
+      it "succeeds when given summary was updated by matching value" do
+        expect do
+          Yabeda.test_summary.observe({}, 2)
+        end.to observe_yabeda_summary(Yabeda.test_summary).with(be_even)
+      end
+
+      it "fails when given summary was updated with any other value" do
+        expect do
+          expect do
+            Yabeda.other_summary.observe({}, 1)
+          end.to observe_yabeda_summary(Yabeda.test_summary).with(2)
+        end.to raise_error(RSpec::Expectations::ExpectationNotMetError)
+      end
+    end
+
+    context "with tags specified" do
+      it "succeeds when tags are match" do
+        expect do
+          Yabeda.test_summary.observe({ foo: :bar }, 42)
+        end.to observe_yabeda_summary(Yabeda.test_summary).with_tags(foo: :bar)
+      end
+
+      it "fails when tags doesn't match" do
+        expect do
+          expect do
+            Yabeda.other_summary.observe({ foo: :bar, baz: :qux }, 15)
+          end.to observe_yabeda_summary(Yabeda.test_summary).with_tags(foo: :bar, baz: :boom)
+        end.to raise_error(RSpec::Expectations::ExpectationNotMetError)
+      end
+
+      it "succeeds when subset of tags was specified and it matches" do
+        expect do
+          expect do
+            Yabeda.other_summary.observe({ foo: :bar, baz: :qux }, 0.001)
+          end.to observe_yabeda_summary(Yabeda.test_summary).with_tags(foo: :bar)
+        end.to raise_error(RSpec::Expectations::ExpectationNotMetError)
+      end
+    end
+
+    context "with negated expect" do
+      it "succeeds when given summary wasn't updated" do
+        expect do
+          # nothing here
+        end.not_to observe_yabeda_summary(Yabeda.test_summary)
+      end
+
+      it "fails when given summary was updated" do
+        expect do
+          expect do
+            Yabeda.test_summary.observe({}, 42)
+          end.not_to observe_yabeda_summary(Yabeda.test_summary)
+        end.to raise_error(RSpec::Expectations::ExpectationNotMetError)
+      end
+
+      context "with set specified" do
+        it "throws error as this behavior can lead to too permissive tests" do
+          expect do
+            expect do
+              Yabeda.test_summary.observe({}, 42)
+            end.not_to observe_yabeda_summary(Yabeda.test_summary).with(42)
+          end.to raise_error(NotImplementedError)
+        end
+      end
+
+      context "with tags specified" do
+        it "fails when tags are match" do
+          expect do
+            expect do
+              Yabeda.test_summary.observe({ foo: :bar }, 42)
+            end.not_to observe_yabeda_summary(Yabeda.test_summary).with_tags(foo: :bar)
+          end.to raise_error(RSpec::Expectations::ExpectationNotMetError)
+        end
+
+        it "succeeds when tags doesn't match" do
+          expect do
+            Yabeda.test_summary.observe({ foo: :bar, baz: :qux }, 5)
+          end.not_to observe_yabeda_summary(Yabeda.test_summary).with_tags(foo: :bar, baz: :boom)
+        end
+
+        it "fails when subset of tags was specified and set tags matches this subset" do
+          expect do
+            expect do
+              Yabeda.test_summary.observe({ foo: :bar, baz: :qux }, 0.001)
+            end.not_to observe_yabeda_summary(Yabeda.test_summary).with_tags(foo: :bar)
+          end.to raise_error(RSpec::Expectations::ExpectationNotMetError)
+        end
+      end
+    end
+
+    it "allows to pass summary name instead of metric object" do
+      expect do
+        Yabeda.test_summary.observe({}, 0.013)
+      end.to observe_yabeda_summary(:test_summary).with(0.01..0.02)
+    end
+  end
+end
diff --git a/spec/yabeda/summary_spec.rb b/spec/yabeda/summary_spec.rb
new file mode 100644
index 0000000..0a27dae
--- /dev/null
+++ b/spec/yabeda/summary_spec.rb
@@ -0,0 +1,57 @@
+# frozen_string_literal: true
+
+RSpec.describe Yabeda::Summary do
+  subject(:observe_summary) { summary.observe(tags, metric_value) }
+
+  let(:tags) { { foo: "bar" } }
+  let(:metric_value) { 10 }
+  let(:block) { proc { 1 + 1 } }
+  let(:summary) { Yabeda.test_summary }
+  let(:built_tags) { { built_foo: "built_bar" } }
+  let(:adapter) { instance_double(Yabeda::BaseAdapter, perform_summary_observe!: true, register!: true) }
+
+  before do
+    Yabeda.configure { summary :test_summary }
+    Yabeda.configure! unless Yabeda.already_configured?
+    allow(Yabeda::Tags).to receive(:build).with(tags, anything).and_return(built_tags)
+    Yabeda.register_adapter(:test_adapter, adapter)
+  end
+
+  context "with value given" do
+    it { is_expected.to eq(metric_value) }
+
+    it "execute perform_summary_observe! method of adapter" do
+      observe_summary
+      expect(adapter).to have_received(:perform_summary_observe!).with(summary, built_tags, metric_value)
+    end
+  end
+
+  context "with block given" do
+    subject(:observe_summary) { summary.observe(tags, &block) }
+
+    let(:block) { proc { sleep(0.02) } }
+
+    it { is_expected.to be_between(0.01, 0.05) } # Ruby can sleep more or less than requested
+
+    it "execute perform_summary_observe! method of adapter" do
+      observe_summary
+      expect(adapter).to have_received(:perform_summary_observe!).with(summary, built_tags, be_between(0.01, 0.05))
+    end
+  end
+
+  context "with both value and block provided" do
+    subject(:observe_summary) { summary.observe(tags, metric_value, &block) }
+
+    it "raises an argument error" do
+      expect { observe_summary }.to raise_error(ArgumentError)
+    end
+  end
+
+  context "with both value and block omitted" do
+    subject(:observe_summary) { summary.observe(tags) }
+
+    it "raises an argument error" do
+      expect { observe_summary }.to raise_error(ArgumentError)
+    end
+  end
+end