diff --git a/src/spectator/dsl/example_factory.cr b/src/spectator/dsl/example_factory.cr
index 1610461..97345da 100644
--- a/src/spectator/dsl/example_factory.cr
+++ b/src/spectator/dsl/example_factory.cr
@@ -1,8 +1,13 @@
 module Spectator::DSL
+  # Creates instances of examples from a specified class.
   class ExampleFactory
+    # Creates the factory.
+    # The type passed to this constructor must be a sub-type of `Example`.
     def initialize(@example_type : Example.class)
     end
 
+    # Constructs a new example instance and returns it.
+    # The `group` and `sample_valuees` are passed to `Example#initialize`.
     def build(group : ExampleGroup, sample_values : Internals::SampleValues) : Example
       @example_type.new(group, sample_values)
     end
diff --git a/src/spectator/dsl/example_group_builder.cr b/src/spectator/dsl/example_group_builder.cr
index 9d939e4..93dc958 100644
--- a/src/spectator/dsl/example_group_builder.cr
+++ b/src/spectator/dsl/example_group_builder.cr
@@ -1,38 +1,57 @@
 module Spectator::DSL
+  # Base class for building all example groups.
   abstract class ExampleGroupBuilder
+    # Type alias for valid children of example groups.
+    # NOTE: `NestedExampleGroupBuilder` is used instead of `ExampleGroupBuilder`.
+    # That is because `RootExampleGroupBuilder` also inherits from this class,
+    # and the root example group can't be a child.
     alias Child = ExampleFactory | NestedExampleGroupBuilder
 
+    # Factories and builders for all examples and groups.
     @children = [] of Child
+
+    # Hooks added to the group so far.
     @before_all_hooks = [] of ->
     @before_each_hooks = [] of ->
     @after_all_hooks = [] of ->
     @after_each_hooks = [] of ->
     @around_each_hooks = [] of Proc(Nil) ->
 
+    # Adds a new example factory or group builder to this group.
     def add_child(child : Child)
       @children << child
     end
 
+    # Adds a hook to run before all examples (and nested examples) in this group.
     def add_before_all_hook(block : ->) : Nil
       @before_all_hooks << block
     end
 
+    # Adds a hook to run before each example (and nested example) in this group.
     def add_before_each_hook(block : ->) : Nil
       @before_each_hooks << block
     end
 
+    # Adds a hook to run after all examples (and nested examples) in this group.
     def add_after_all_hook(block : ->) : Nil
       @after_all_hooks << block
     end
 
+    # Adds a hook to run after each example (and nested example) in this group.
     def add_after_each_hook(block : ->) : Nil
       @after_each_hooks << block
     end
 
+    # Adds a hook to run around each example (and nested example) in this group.
+    # The block of code will be given another proc as an argument.
+    # It is expected that the block will call the proc.
     def add_around_each_hook(block : Proc(Nil) ->) : Nil
       @around_each_hooks << block
     end
 
+    # Constructs an `ExampleHooks` instance with all the hooks defined for this group.
+    # This method should be only when the group is being built,
+    # otherwise some hooks may be missing.
     private def hooks
       ExampleHooks.new(
         @before_all_hooks,
diff --git a/src/spectator/dsl/given_example_group_builder.cr b/src/spectator/dsl/given_example_group_builder.cr
index 3346219..64c1fc4 100644
--- a/src/spectator/dsl/given_example_group_builder.cr
+++ b/src/spectator/dsl/given_example_group_builder.cr
@@ -1,23 +1,63 @@
 require "./nested_example_group_builder"
 
 module Spectator::DSL
+  # Specialized example group builder for "given" groups.
+  # The type parameter `T` should be the type of each element in the given collection.
+  # This builder creates a container group with groups inside for each item in the collection.
+  # The hooks are only defined for the container group.
+  # By doing so, the hooks are defined once, are inherited, and use less memory.
   class GivenExampleGroupBuilder(T) < NestedExampleGroupBuilder
+    # Creates a new group builder.
+    # The value for `what` should be the text the user specified for the collection.
+    # The `collection` is the actual array of items to create examples for.
+    #
+    # In this code:
+    # ```
+    # given random_integers do
+    #   # ...
+    # end
+    # ```
+    # The `what` value would be "random_integers"
+    # and the collection would contain the items returned by calling `random_integers`.
+    #
+    # The `symbol` is passed along to the sample values
+    # so that the example code can retrieve the current item from the collection.
+    # The symbol should be unique.
     def initialize(what : String, @collection : Array(T), @symbol : Symbol)
       super(what)
     end
 
+    # Builds the example group.
+    # A new `NestedExampleGroup` will be returned
+    # which can have instances of `Example` and `ExampleGroup` nested in it.
+    # The `parent` should be the group that contains this group.
+    # The `sample_values` will be given to all of the examples (and groups) nested in this group.
     def build(parent : ExampleGroup, sample_values : Internals::SampleValues) : NestedExampleGroup
+      # This creates the container for the sub-groups.
+      # The hooks are defined here, instead of repeating for each sub-group.
       NestedExampleGroup.new(@what, parent, hooks).tap do |group|
+        # Set the container group's children to be sub-groups for each item in the collection.
         group.children = @collection.map do |value|
+          # Create a sub-group for each item in the collection.
           build_sub_group(group, sample_values, value).as(ExampleComponent)
         end
       end
     end
 
+    # Builds a sub-group for one item in the collection.
+    # The `parent` should be the container group currently being built by the `#build` call.
+    # The `sample_values` should be the same as what was passed to the `#build` call.
+    # The `value` is the current item in the collection.
+    # The value will be added to the sample values for the sub-group,
+    # so it shouldn't be added prior to calling this method.
     private def build_sub_group(parent : ExampleGroup, sample_values : Internals::SampleValues, value : T) : NestedExampleGroup
-      sub_values = sample_values.add(@symbol, @symbol.to_s, value) # TODO: Use real name instead of symbol as string.
+      # Add the value to sample values for this sub-group.
+      # TODO: Use real name instead of symbol as string.
+      sub_values = sample_values.add(@symbol, @symbol.to_s, value)
       NestedExampleGroup.new(value.to_s, parent, ExampleHooks.empty).tap do |group|
+        # Set the sub-group's children to built versions of the children from this instance.
         group.children = @children.map do |child|
+          # Build the child and up-cast to prevent type errors.
           child.build(group, sub_values).as(ExampleComponent)
         end
       end
diff --git a/src/spectator/dsl/nested_example_group_builder.cr b/src/spectator/dsl/nested_example_group_builder.cr
index 3d6af2d..a05b428 100644
--- a/src/spectator/dsl/nested_example_group_builder.cr
+++ b/src/spectator/dsl/nested_example_group_builder.cr
@@ -1,11 +1,34 @@
 module Spectator::DSL
+  # Standard example group builder.
+  # Creates groups of examples and nested groups.
   class NestedExampleGroupBuilder < ExampleGroupBuilder
+    # Creates a new group builder.
+    # The value for `what` should be the context for the group.
+    #
+    # For example, in these samples:
+    # ```
+    # describe String do
+    #   # ...
+    #   context "with an empty string" do
+    #     # ...
+    #   end
+    # end
+    # ```
+    # The value would be "String" for the describe block
+    # and "with an empty string" for the context block.
     def initialize(@what : String)
     end
 
+    # Builds the example group.
+    # A new `NestedExampleGroup` will be returned
+    # which can have instances of `Example` and `ExampleGroup` nested in it.
+    # The `parent` should be the group that contains this group.
+    # The `sample_values` will be given to all of the examples (and groups) nested in this group.
     def build(parent : ExampleGroup, sample_values : Internals::SampleValues) : NestedExampleGroup
       NestedExampleGroup.new(@what, parent, hooks).tap do |group|
+        # Set the group's children to built versions of the children from this instance.
         group.children = @children.map do |child|
+          # Build the child and up-cast to prevent type errors.
           child.build(group, sample_values).as(ExampleComponent)
         end
       end
diff --git a/src/spectator/dsl/root_example_group_builder.cr b/src/spectator/dsl/root_example_group_builder.cr
index 6321d25..87c7097 100644
--- a/src/spectator/dsl/root_example_group_builder.cr
+++ b/src/spectator/dsl/root_example_group_builder.cr
@@ -1,8 +1,15 @@
 module Spectator::DSL
+  # Top-level example group builder.
+  # There should only be one instance of this class,
+  # and it should be at the top of the spec "tree".
   class RootExampleGroupBuilder < ExampleGroupBuilder
+    # Creates a `RootExampleGroup` which can have instances of `Example` and `ExampleGroup` nested in it.
+    # The `sample_values` will be given to all of the examples (and groups) nested in this group.
     def build(sample_values : Internals::SampleValues) : RootExampleGroup
       RootExampleGroup.new(hooks).tap do |group|
+        # Set the group's children to built versions of the children from this instance.
         group.children = @children.map do |child|
+          # Build the child and up-cast to prevent type errors.
           child.build(group, sample_values).as(ExampleComponent)
         end
       end