diff --git a/src/Avalonia.Styling/Styling/Activators/AndActivator.cs b/src/Avalonia.Styling/Styling/Activators/AndActivator.cs
index 8ab281e8d0..0e1e3b565b 100644
--- a/src/Avalonia.Styling/Styling/Activators/AndActivator.cs
+++ b/src/Avalonia.Styling/Styling/Activators/AndActivator.cs
@@ -4,6 +4,10 @@ using System.Collections.Generic;
 
 namespace Avalonia.Styling.Activators
 {
+    /// <summary>
+    /// An aggregate <see cref="IStyleActivator"/> which is active when all of its inputs are
+    /// active.
+    /// </summary>
     internal class AndActivator : StyleActivatorBase, IStyleActivatorSink
     {
         private List<IStyleActivator>? _sources;
diff --git a/src/Avalonia.Styling/Styling/Activators/AndActivatorBuilder.cs b/src/Avalonia.Styling/Styling/Activators/AndActivatorBuilder.cs
index 318988b3c5..b831c330f8 100644
--- a/src/Avalonia.Styling/Styling/Activators/AndActivatorBuilder.cs
+++ b/src/Avalonia.Styling/Styling/Activators/AndActivatorBuilder.cs
@@ -2,6 +2,13 @@
 
 namespace Avalonia.Styling.Activators
 {
+    /// <summary>
+    /// Builds an <see cref="AndActivator"/>.
+    /// </summary>
+    /// <remarks>
+    /// When ANDing style activators, if there is more than one input then creates an instance of
+    /// <see cref="AndActivator"/>. If there is only one input, returns the input directly.
+    /// </remarks>
     internal struct AndActivatorBuilder
     {
         private IStyleActivator? _single;
diff --git a/src/Avalonia.Styling/Styling/Activators/NotActivator.cs b/src/Avalonia.Styling/Styling/Activators/NotActivator.cs
index 4c152a8f0f..1bb6ed3cd2 100644
--- a/src/Avalonia.Styling/Styling/Activators/NotActivator.cs
+++ b/src/Avalonia.Styling/Styling/Activators/NotActivator.cs
@@ -2,6 +2,9 @@
 
 namespace Avalonia.Styling.Activators
 {
+    /// <summary>
+    /// An <see cref="IStyleActivator"/> which inverts the state of an input activator.
+    /// </summary>
     internal class NotActivator : StyleActivatorBase, IStyleActivatorSink
     {
         private readonly IStyleActivator _source;
diff --git a/src/Avalonia.Styling/Styling/Activators/OrActivator.cs b/src/Avalonia.Styling/Styling/Activators/OrActivator.cs
index 0220265e10..fcb7d71e60 100644
--- a/src/Avalonia.Styling/Styling/Activators/OrActivator.cs
+++ b/src/Avalonia.Styling/Styling/Activators/OrActivator.cs
@@ -4,6 +4,10 @@ using System.Collections.Generic;
 
 namespace Avalonia.Styling.Activators
 {
+    /// <summary>
+    /// An aggregate <see cref="IStyleActivator"/> which is active when any of its inputs are
+    /// active.
+    /// </summary>
     internal class OrActivator : StyleActivatorBase, IStyleActivatorSink
     {
         private List<IStyleActivator>? _sources;
diff --git a/src/Avalonia.Styling/Styling/Activators/OrActivatorBuilder.cs b/src/Avalonia.Styling/Styling/Activators/OrActivatorBuilder.cs
index ee7731e0ea..4b3fbcfca5 100644
--- a/src/Avalonia.Styling/Styling/Activators/OrActivatorBuilder.cs
+++ b/src/Avalonia.Styling/Styling/Activators/OrActivatorBuilder.cs
@@ -2,6 +2,13 @@
 
 namespace Avalonia.Styling.Activators
 {
+    /// <summary>
+    /// Builds an <see cref="OrActivator"/>.
+    /// </summary>
+    /// <remarks>
+    /// When ORing style activators, if there is more than one input then creates an instance of
+    /// <see cref="OrActivator"/>. If there is only one input, returns the input directly.
+    /// </remarks>
     internal struct OrActivatorBuilder
     {
         private IStyleActivator? _single;
diff --git a/src/Avalonia.Styling/Styling/Activators/PropertyEqualsActivator.cs b/src/Avalonia.Styling/Styling/Activators/PropertyEqualsActivator.cs
index abf3c1717e..9e30e4fa14 100644
--- a/src/Avalonia.Styling/Styling/Activators/PropertyEqualsActivator.cs
+++ b/src/Avalonia.Styling/Styling/Activators/PropertyEqualsActivator.cs
@@ -4,6 +4,9 @@
 
 namespace Avalonia.Styling.Activators
 {
+    /// <summary>
+    /// An <see cref="IStyleActivator"/> which listens to a property value on a control.
+    /// </summary>
     internal class PropertyEqualsActivator : StyleActivatorBase, IObserver<object>
     {
         private readonly IStyleable _control;
diff --git a/src/Avalonia.Styling/Styling/Activators/StyleActivatorBase.cs b/src/Avalonia.Styling/Styling/Activators/StyleActivatorBase.cs
index 725547ed05..578098b2b0 100644
--- a/src/Avalonia.Styling/Styling/Activators/StyleActivatorBase.cs
+++ b/src/Avalonia.Styling/Styling/Activators/StyleActivatorBase.cs
@@ -2,6 +2,9 @@
 
 namespace Avalonia.Styling.Activators
 {
+    /// <summary>
+    /// Base class implementation of <see cref="IStyleActivator"/>.
+    /// </summary>
     internal abstract class StyleActivatorBase : IStyleActivator
     {
         private IStyleActivatorSink? _sink;
diff --git a/src/Avalonia.Styling/Styling/Activators/StyleClassActivator.cs b/src/Avalonia.Styling/Styling/Activators/StyleClassActivator.cs
index 906a8303cb..c884b6ac43 100644
--- a/src/Avalonia.Styling/Styling/Activators/StyleClassActivator.cs
+++ b/src/Avalonia.Styling/Styling/Activators/StyleClassActivator.cs
@@ -6,6 +6,10 @@ using Avalonia.Collections;
 
 namespace Avalonia.Styling.Activators
 {
+    /// <summary>
+    /// An <see cref="IStyleActivator"/> which is active when a set of classes match those on a
+    /// control.
+    /// </summary>
     internal sealed class StyleClassActivator : StyleActivatorBase
     {
         private readonly IList<string> _match;
diff --git a/src/Avalonia.Styling/Styling/PropertySetterBindingInstance.cs b/src/Avalonia.Styling/Styling/PropertySetterBindingInstance.cs
index 12055446a5..0741d38146 100644
--- a/src/Avalonia.Styling/Styling/PropertySetterBindingInstance.cs
+++ b/src/Avalonia.Styling/Styling/PropertySetterBindingInstance.cs
@@ -7,6 +7,11 @@ using Avalonia.Reactive;
 
 namespace Avalonia.Styling
 {
+    /// <summary>
+    /// A <see cref="Setter"/> which has been instanced on a control and has an
+    /// <see cref="IBinding"/> as its value.
+    /// </summary>
+    /// <typeparam name="T">The target property type.</typeparam>
     internal class PropertySetterBindingInstance<T> : SingleSubscriberObservableBase<BindingValue<T>>,
         ISubject<BindingValue<T>>,
         ISetterInstance
diff --git a/src/Avalonia.Styling/Styling/PropertySetterInstance.cs b/src/Avalonia.Styling/Styling/PropertySetterInstance.cs
index 530a09a01a..689438dfd7 100644
--- a/src/Avalonia.Styling/Styling/PropertySetterInstance.cs
+++ b/src/Avalonia.Styling/Styling/PropertySetterInstance.cs
@@ -6,6 +6,10 @@ using Avalonia.Reactive;
 
 namespace Avalonia.Styling
 {
+    /// <summary>
+    /// A <see cref="Setter"/> which has been instance on a control.
+    /// </summary>
+    /// <typeparam name="T">The target property type.</typeparam>
     internal class PropertySetterInstance<T> : SingleSubscriberObservableBase<BindingValue<T>>,
         ISetterInstance
     {
diff --git a/src/Avalonia.Styling/Styling/Selector.cs b/src/Avalonia.Styling/Styling/Selector.cs
index f14e1ad232..0404ee14ae 100644
--- a/src/Avalonia.Styling/Styling/Selector.cs
+++ b/src/Avalonia.Styling/Styling/Selector.cs
@@ -110,7 +110,7 @@ namespace Avalonia.Styling
 
             // Selectors are stored from right-to-left, so we recurse into the selector in order to
             // reverse this order, because the type selector will be on the left and is our best
-            // oppurtunity exit early.
+            // opportunity to exit early.
             if (previous != null && !previous.IsCombinator)
             {
                 var previousMatch = Match(control, previous, subscribe, ref activators, ref combinator);
diff --git a/src/Avalonia.Styling/Styling/StyleInstance.cs b/src/Avalonia.Styling/Styling/StyleInstance.cs
index 7919d2ca28..c48690e96e 100644
--- a/src/Avalonia.Styling/Styling/StyleInstance.cs
+++ b/src/Avalonia.Styling/Styling/StyleInstance.cs
@@ -8,6 +8,9 @@ using Avalonia.Styling.Activators;
 
 namespace Avalonia.Styling
 {
+    /// <summary>
+    /// A <see cref="Style"/> which has been instanced on a control.
+    /// </summary>
     internal class StyleInstance : IStyleInstance, IStyleActivatorSink
     {
         private readonly List<ISetterInstance>? _setters;