diff --git a/html.go b/html.go
index c0f278c..763afd5 100644
--- a/html.go
+++ b/html.go
@@ -22,20 +22,21 @@ import (
 	"strings"
 )
 
+// Html renderer configuration options.
 const (
-	HTML_SKIP_HTML = 1 << iota
-	HTML_SKIP_STYLE
-	HTML_SKIP_IMAGES
-	HTML_SKIP_LINKS
-	HTML_SAFELINK
-	HTML_TOC
-	HTML_OMIT_CONTENTS
-	HTML_COMPLETE_PAGE
-	HTML_GITHUB_BLOCKCODE
-	HTML_USE_XHTML
-	HTML_USE_SMARTYPANTS
-	HTML_SMARTYPANTS_FRACTIONS
-	HTML_SMARTYPANTS_LATEX_DASHES
+	HTML_SKIP_HTML                = 1 << iota // skip preformatted HTML blocks
+	HTML_SKIP_STYLE                           // skip embedded <style> elements
+	HTML_SKIP_IMAGES                          // skip embedded images
+	HTML_SKIP_LINKS                           // skip all links
+	HTML_SAFELINK                             // only link to trusted protocols
+	HTML_TOC                                  // generate a table of contents
+	HTML_OMIT_CONTENTS                        // skip the main contents (for a standalone table of contents)
+	HTML_COMPLETE_PAGE                        // generate a complete HTML page
+	HTML_GITHUB_BLOCKCODE                     // use github fenced code rendering rules
+	HTML_USE_XHTML                            // generate XHTML output instead of HTML
+	HTML_USE_SMARTYPANTS                      // enable smart punctuation substitutions
+	HTML_SMARTYPANTS_FRACTIONS                // enable smart fractions (with HTML_USE_SMARTYPANTS)
+	HTML_SMARTYPANTS_LATEX_DASHES             // enable LaTeX-style dashes (with HTML_USE_SMARTYPANTS)
 )
 
 // Html is a type that implements the Renderer interface for HTML output.
diff --git a/markdown.go b/markdown.go
index a42807a..a1e90a1 100644
--- a/markdown.go
+++ b/markdown.go
@@ -13,6 +13,9 @@
 //
 //
 
+// Blackfriday markdown processor.
+//
+// Translates plain text with simple formatting rules into HTML or LaTeX.
 package blackfriday
 
 import (
@@ -25,15 +28,15 @@ const VERSION = "0.6"
 // These are the supported markdown parsing extensions.
 // OR these values together to select multiple extensions.
 const (
-	EXTENSION_NO_INTRA_EMPHASIS = 1 << iota
-	EXTENSION_TABLES
-	EXTENSION_FENCED_CODE
-	EXTENSION_AUTOLINK
-	EXTENSION_STRIKETHROUGH
-	EXTENSION_LAX_HTML_BLOCKS
-	EXTENSION_SPACE_HEADERS
-	EXTENSION_HARD_LINE_BREAK
-	EXTENSION_TAB_SIZE_EIGHT
+	EXTENSION_NO_INTRA_EMPHASIS = 1 << iota // ignore emphasis markers inside words
+	EXTENSION_TABLES                        // render tables
+	EXTENSION_FENCED_CODE                   // render fenced code blocks
+	EXTENSION_AUTOLINK                      // detect embedded URLs that are not explicitly marked
+	EXTENSION_STRIKETHROUGH                 // strikethrough text using ~~test~~
+	EXTENSION_LAX_HTML_BLOCKS               // loosen up HTML block parsing rules
+	EXTENSION_SPACE_HEADERS                 // be strict about prefix header rules
+	EXTENSION_HARD_LINE_BREAK               // translate newlines into line breaks
+	EXTENSION_TAB_SIZE_EIGHT                // expand tabs to eight spaces instead of four
 )
 
 // These are the possible flag values for the link renderer.