diff --git a/HTMLKit/HTMLNamespaces.h b/HTMLKit/HTMLNamespaces.h
index 112161e..fb7badd 100644
--- a/HTMLKit/HTMLNamespaces.h
+++ b/HTMLKit/HTMLNamespaces.h
@@ -6,8 +6,18 @@
 //  Copyright (c) 2014 BrainCookie. All rights reserved.
 //
 
+/**
+ HTML Namespaces
+ https://html.spec.whatwg.org/multipage/infrastructure.html#namespaces
+ */
 typedef NS_ENUM(NSInteger, HTMLNamespace)
 {
+	/** The default HTML namespace. */
 	HTMLNamespaceHTML,
+
+	/** The namespace for most of the <math> elements. */
 	HTMLNamespaceMathML,
+
+	/** The namespace for most of the <svg> elements. */
+	HTMLNamespaceSVG
 };
diff --git a/HTMLKit/HTMLNodeFilter.h b/HTMLKit/HTMLNodeFilter.h
index e90cd86..376f885 100644
--- a/HTMLKit/HTMLNodeFilter.h
+++ b/HTMLKit/HTMLNodeFilter.h
@@ -10,6 +10,10 @@
 
 NS_ASSUME_NONNULL_BEGIN
 
+/**
+ The node filter's value when applied to a given HTML node. The node filter can either accept a node, skip it, or 
+ reject it. Rejecting a node means skipping the node itself and all of it descendants.
+ */
 typedef NS_ENUM(unsigned short, HTMLNodeFilterValue)
 {
 	HTMLNodeFilterAccept = 1,
@@ -17,6 +21,12 @@ typedef NS_ENUM(unsigned short, HTMLNodeFilterValue)
 	HTMLNodeFilterSkip = 3
 };
 
+/**
+ The show options for the HTML node iterator and tree walker.
+ 
+ @see HTMLNodeIterator
+ @see HTMLTreeWalker
+ */
 typedef NS_OPTIONS(unsigned long, HTMLNodeFilterShowOptions)
 {
 	HTMLNodeFilterShowAll = 0xFFFFFFFF,
@@ -33,16 +43,36 @@ typedef NS_OPTIONS(unsigned long, HTMLNodeFilterShowOptions)
 
 @class HTMLNode;
 
+/**
+ A HTML Node Filter which can be used with a node iterator or a tree walker.
+ 
+ @see HTMLNodeIterator
+ @see HTMLTreeWalker
+ */
 @protocol HTMLNodeFilter <NSObject>
-
+@required
+/**
+ The implementation should return a HTMLNodeFilterValue to indicate accepting, skipping or rejecting a node.
+ 
+ @param node The node to be filtered.
+ @returns `HTMLNodeFilterAccept` if accepted, `HTMLNodeFilterSkip` if skipped, or `HTMLNodeFilterReject` if rejected.
+ */
 - (HTMLNodeFilterValue)acceptNode:(HTMLNode *)node;
 
 @end
 
 #pragma mark - Block Filter
 
+/**
+ A concrete block-based HTML Node Filter implementation.
+ */
 @interface HTMLNodeFilterBlock : NSObject <HTMLNodeFilter>
 
+/**
+ Initializes and returns a new instance of this filter.
+ 
+ @param block The block to apply on each node to be filtered.
+ */
 + (instancetype)filterWithBlock:(HTMLNodeFilterValue (^)(HTMLNode *node))block;
 
 @end
@@ -51,8 +81,16 @@ typedef NS_OPTIONS(unsigned long, HTMLNodeFilterShowOptions)
 
 @class CSSSelector;
 
+/**
+ A concrete css-selector-based HTML Node Filter implementation.
+ */
 @interface HTMLSelectorNodeFilter : NSObject <HTMLNodeFilter>
 
+/**
+ Initializes and returns a new instance of this filter.
+
+ @param selector The selector to apply on each node to be filtered.
+ */
 + (instancetype)filterWithSelector:(CSSSelector *)selector;
 
 @end
diff --git a/HTMLKit/HTMLNodeIterator.h b/HTMLKit/HTMLNodeIterator.h
index f8af8a6..946aeb7 100644
--- a/HTMLKit/HTMLNodeIterator.h
+++ b/HTMLKit/HTMLNodeIterator.h
@@ -13,26 +13,81 @@ NS_ASSUME_NONNULL_BEGIN
 
 @class HTMLNode;
 
+/**
+ A HTML Node Iterator, which iterates the nodes in the DOM in tree order, i.e. depth-first traversal of the tree.
+
+ https://dom.spec.whatwg.org/#interface-nodeiterator
+ */
 @interface HTMLNodeIterator : NSEnumerator
 
+/**
+ The root element of this iterator, i.e. the traversed tree is rooted at this element.
+ */
 @property (nonatomic, strong, readonly) HTMLNode *root;
+
+/**
+ The current reference node.
+ */
 @property (nonatomic, strong, readonly) HTMLNode *referenceNode;
+
+/**
+ Whether the iterator's pointer is before the reference node.
+ */
 @property (nonatomic, assign, readonly) BOOL pointerBeforeReferenceNode;
+
+/**
+ The iterator's show options. These options control what types of elements are shown or skipped during iteration.
+
+ @see HTMLNodeFilterShowOptions
+ */
 @property (nonatomic, assign, readonly) HTMLNodeFilterShowOptions whatToShow;
-@property (nonatomic, strong, readonly) id<HTMLNodeFilter> filter;
 
-+ (instancetype)iteratorWithNode:(HTMLNode *)node
-					 showOptions:(HTMLNodeFilterShowOptions)showOptions
-						  filter:(nullable HTMLNodeFilterValue (^)(HTMLNode *node))filter;
+/**
+ A node filter, that is applied to each node during iteration.
 
+ @see HTMLNodeFilter
+ */
+@property (nonatomic, strong, readonly, nullable) id<HTMLNodeFilter> filter;
+
+
+/**
+ Initializes a new node iterator with no filter and HTMLNodeFilterShowAll show options.
+
+ @param node The root node.
+ @returns A new instance of a node iterator.
+ */
 - (instancetype)initWithNode:(HTMLNode *)node;
+
+/**
+ Initializes a new node iterator with HTMLNodeFilterShowAll show options.
+
+ @param node The root node.
+ @param filter The node filter to use.
+ @returns A new instance of a node iterator.
+ */
 - (instancetype)initWithNode:(HTMLNode *)node
 					  filter:(nullable id<HTMLNodeFilter>)filter;
+
+/**
+ Initializes a new node iterator.
+
+ @param node The root node.
+ @param showOptions The show options for the iterator.
+ @param filter The node filter to use.
+ @returns A new instance of a node iterator.
+ */
 - (instancetype)initWithNode:(HTMLNode *)node
 				 showOptions:(HTMLNodeFilterShowOptions)showOptions
 					  filter:(nullable id<HTMLNodeFilter>)filter;
 
+/**
+ @returns The next iterated node in tree order, `nil` if there are no more nodes to iterate.
+ */
 - (nullable HTMLNode *)nextNode;
+
+/**
+ @returns The previous iterated node in tree order, `nil` if there are no more nodes to iterate.
+ */
 - (nullable HTMLNode *)previousNode;
 
 @end
diff --git a/HTMLKit/HTMLNodeTraversal.h b/HTMLKit/HTMLNodeTraversal.h
index ee2bf7e..bd40058 100644
--- a/HTMLKit/HTMLNodeTraversal.h
+++ b/HTMLKit/HTMLNodeTraversal.h
@@ -6,6 +6,10 @@
 //  Copyright (c) 2015 BrainCookie. All rights reserved.
 //
 
+///------------------------------------------------------
+/// HTMLKit private header
+///------------------------------------------------------
+
 #import <Foundation/Foundation.h>
 #import "HTMLNodeFilter.h"
 
diff --git a/HTMLKit/HTMLQuirksMode.h b/HTMLKit/HTMLQuirksMode.h
index 3ad4920..2c6008d 100644
--- a/HTMLKit/HTMLQuirksMode.h
+++ b/HTMLKit/HTMLQuirksMode.h
@@ -8,6 +8,10 @@
 
 #import "NSString+HTMLKit.h"
 
+/**
+ HTML quirks modes
+ https://html.spec.whatwg.org/multipage/infrastructure.html#quirks-mode
+ */
 typedef NS_ENUM(short, HTMLQuirksMode)
 {
 	HTMLQuirksModeNoQuirks,
diff --git a/HTMLKit/HTMLTreeWalker.h b/HTMLKit/HTMLTreeWalker.h
index ac425c6..07a7f08 100644
--- a/HTMLKit/HTMLTreeWalker.h
+++ b/HTMLKit/HTMLTreeWalker.h
@@ -13,26 +13,102 @@ NS_ASSUME_NONNULL_BEGIN
 
 @class HTMLNode;
 
+/**
+ A HTML Tree Walker. Used to "walk" the DOM tree in all directions, i.e. it can traverse from a given node to its parent,
+ child, next, or previous sibling.
+
+ https://dom.spec.whatwg.org/#interface-treewalker
+ */
 @interface HTMLTreeWalker : NSObject
 
+/**
+ The root element of this tree walker, i.e. the traversed tree is rooted at this element.
+ */
 @property (nonatomic, strong, readonly) HTMLNode *root;
+
+/**
+ The iterator's show options. These options control what types of elements are shown or skipped during tree walking.
+
+ @see HTMLNodeFilterShowOptions
+ */
 @property (nonatomic, assign, readonly) HTMLNodeFilterShowOptions whatToShow;
+
+/**
+ A node filter, that is applied to each node during tree walking.
+
+ @see HTMLNodeFilter
+ */
 @property (nonatomic, strong, readonly, nullable) id<HTMLNodeFilter> filter;
+
+/**
+ The current node at which this walker is standing.
+ */
 @property (nonatomic, strong) HTMLNode *currentNode;
 
+/**
+ Initializes a new tree walker with no filter and HTMLNodeFilterShowAll show options.
+
+ @param node The root node.
+ @param filter The node filter to use.
+ @returns A new instance of a tree walker.
+ */
 - (instancetype)initWithNode:(HTMLNode *)node;
+
+/**
+ Initializes a new tree walker with HTMLNodeFilterShowAll show options.
+
+ @param node The root node.
+ @param filter The node filter to use.
+ @returns A new instance of a tree walker.
+ */
 - (instancetype)initWithNode:(HTMLNode *)node
 					  filter:(nullable id<HTMLNodeFilter>)filter;
+
+/**
+ Initializes a new tree walker.
+
+ @param node The root node.
+ @param showOptions The show options for the walker.
+ @param filter The node filter to use.
+ @returns A new instance of a tree walker.
+ */
 - (instancetype)initWithNode:(HTMLNode *)node
 				 showOptions:(HTMLNodeFilterShowOptions)showOptions
 					  filter:(nullable id<HTMLNodeFilter>)filter;
 
+/**
+ The parent node of the current node.
+ */
 - (nullable HTMLNode *)parentNode;
+
+/**
+ The first child node of the current node.
+ */
 - (nullable HTMLNode *)firstChild;
+
+/**
+ The last child node of the current node.
+ */
 - (nullable HTMLNode *)lastChild;
+
+/**
+ The previous sibling node of the current node.
+ */
 - (nullable HTMLNode *)previousSibling;
+
+/**
+ The next sibling node of the current node.
+ */
 - (nullable HTMLNode *)nextSibling;
+
+/**
+ The previous node of the current node in tree order.
+ */
 - (nullable HTMLNode *)previousNode;
+
+/**
+ The next node of the current node in tree order.
+ */
 - (nullable HTMLNode *)nextNode;
 
 @end