diff --git a/lib/guard/listener.rb b/lib/guard/listener.rb
index c401932..148c3ac 100644
--- a/lib/guard/listener.rb
+++ b/lib/guard/listener.rb
@@ -8,40 +8,60 @@ module Guard
   autoload :Windows, 'guard/listeners/windows'
   autoload :Polling, 'guard/listeners/polling'
 
+  # The Listener is the base class for all listener
+  # implementations.
+  #
   class Listener
 
-    DefaultIgnorePaths = %w[. .. .bundle .git log tmp vendor]
+    DEFAULT_IGNORE_PATHS = %w[. .. .bundle .git log tmp vendor]
+
     attr_accessor :changed_files
     attr_reader :directory, :ignore_paths, :locked
 
-    def self.select_and_init(*a)
+    # Select the appropriate listener implementation for the
+    # current OS and initializes it.
+    #
+    # @param [Array] args the arguments for the listener
+    # @return [Guard::Listener] the chosen listener
+    #
+    def self.select_and_init(*args)
       if mac? && Darwin.usable?
-        Darwin.new(*a)
+        Darwin.new(*args)
       elsif linux? && Linux.usable?
-        Linux.new(*a)
+        Linux.new(*args)
       elsif windows? && Windows.usable?
-        Windows.new(*a)
+        Windows.new(*args)
       else
-        UI.info "Using polling (Please help us to support your system better than that.)"
-        Polling.new(*a)
+        UI.info 'Using polling (Please help us to support your system better than that).'
+        Polling.new(*args)
       end
     end
 
-    def initialize(directory = Dir.pwd, options = {})
+    # Initialize the listener.
+    #
+    # @param [String] directory the root directory to listen to
+    # @param [Hash] options the listener options
+    # @option options [Boolean] relativize_paths use only relative paths
+    # @option options [Array<String>] ignore_paths the paths to ignore by the listener
+    #
+    def initialize(directory = Dir.pwd, options = { })
       @directory           = directory.to_s
-      @sha1_checksums_hash = {}
+      @sha1_checksums_hash = { }
       @relativize_paths    = options.fetch(:relativize_paths, true)
       @changed_files       = []
       @locked              = false
-      @ignore_paths        = DefaultIgnorePaths
-      @ignore_paths        |= options[:ignore_paths] if options[:ignore_paths]
+      @ignore_paths        = DEFAULT_IGNORE_PATHS
+      @ignore_paths |= options[:ignore_paths] if options[:ignore_paths]
 
       update_last_event
       start_reactor
     end
 
+    # Start the listener thread.
+    #
     def start_reactor
       return if ENV["GUARD_ENV"] == 'test'
+
       Thread.new do
         loop do
           if @changed_files != [] && !@locked
@@ -55,75 +75,114 @@ module Guard
       end
     end
 
+    # Start watching the root directory.
+    #
     def start
       watch(@directory)
     end
 
+    # Stop listening for events.
+    #
     def stop
     end
 
+    # Lock the listener to ignore change events.
+    #
     def lock
       @locked = true
     end
 
+    # Unlock the listener to listen again to change events.
+    #
     def unlock
       @locked = false
     end
 
+    # Clear the list of changed files.
+    #
     def clear_changed_files
       @changed_files.clear
     end
 
+    # Store a listener callback.
+    #
+    # @param [Block] callback the callback to store
+    #
     def on_change(&callback)
       @callback = callback
     end
 
+    # Updates the timestamp of the last event.
+    #
     def update_last_event
       @last_event = Time.now
     end
 
-    def modified_files(dirs, options = {})
+    def modified_files(dirs, options = { })
       last_event = @last_event
       update_last_event
       files = potentially_modified_files(dirs, options).select { |path| file_modified?(path, last_event) }
       relativize_paths(files)
     end
 
-    def worker
-      raise NotImplementedError, "should respond to #watch"
-    end
-
-    # register a directory to watch. must be implemented by the subclasses
+    # Register a directory to watch.
+    # Must be implemented by the subclasses.
+    #
+    # @param [String] directory the directory to watch
+    #
     def watch(directory)
       raise NotImplementedError, "do whatever you want here, given the directory as only argument"
     end
 
+    # Get all files that are in the watched directory.
+    #
+    # @return [Array<String>] the list of files
+    #
     def all_files
       potentially_modified_files([@directory], :all => true)
     end
 
-    # scopes all given paths to the current #directory
+    # Scopes all given paths to the current directory.
+    #
+    # @param [Array<String>] paths the paths to change
+    # @return [Array<String>] all paths now relative to the current dir
+    #
     def relativize_paths(paths)
       return paths unless relativize_paths?
       paths.map do |path|
-        path.gsub(%r{^#{@directory}/}, '')
+        path.gsub(%r{^#{ @directory }/}, '')
       end
     end
 
+    # Use relative paths?
+    #
+    # @return [Boolean] whether to use relative or absolute paths
+    #
     def relativize_paths?
       !!@relativize_paths
     end
 
-    # return children of the passed dirs that are not in the ignore_paths list
+    # Removes ignored paths from the directory list.
+    #
+    # @param [Array<String>] dirs the directory to listen to
+    # @param [Array<String>] ignore_paths the paths to ignore
+    # @return children of the passed dirs that are not in the ignore_paths list
+    #
     def exclude_ignored_paths(dirs, ignore_paths = self.ignore_paths)
       Dir.glob(dirs.map { |d| "#{d.sub(%r{/+$}, '')}/*" }, File::FNM_DOTMATCH).reject do |path|
         ignore_paths.include?(File.basename(path))
       end
     end
 
-  private
+    private
 
-    def potentially_modified_files(dirs, options={})
+    # Gets a list of files that are in the modified firectories.
+    #
+    # @param [Array<String>] dirs the list of directories
+    # @param [Hash] options the options
+    # @option options [Symbol] all whether to include all files
+    #
+    def potentially_modified_files(dirs, options = {})
       paths = exclude_ignored_paths(dirs)
 
       if options[:all]
@@ -131,7 +190,7 @@ module Guard
           if File.file?(path)
             array << path
           else
-            array += Dir.glob("#{path}/**/*", File::FNM_DOTMATCH).select { |p| File.file?(p) }
+            array += Dir.glob("#{ path }/**/*", File::FNM_DOTMATCH).select { |p| File.file?(p) }
           end
           array
         end
@@ -140,9 +199,17 @@ module Guard
       end
     end
 
+    # Test if the file content has changed.
+    #
     # Depending on the filesystem, mtime/ctime is probably only precise to the second, so round
     # both values down to the second for the comparison.
+    #
     # ctime is used only on == comparison to always catches Rails 3.1 Assets pipelined on Mac OSX
+    #
+    # @param [String] path the file path
+    # @param [Time] last_event the time of the last event
+    # @return [Boolean] Whether the file content has changed or not.
+    #
     def file_modified?(path, last_event)
       ctime = File.ctime(path).to_i
       mtime = File.mtime(path).to_i
@@ -158,6 +225,12 @@ module Guard
       false
     end
 
+    # Tests if the file content has been modified by
+    # comparing the SHA1 checksum.
+    #
+    # @param [String] path the file path
+    # @param [String] sha1_checksum the checksum of the file
+    #
     def file_content_modified?(path, sha1_checksum)
       if @sha1_checksums_hash[path] != sha1_checksum
         set_sha1_checksums_hash(path, sha1_checksum)
@@ -167,22 +240,44 @@ module Guard
       end
     end
 
+    # Set the current checksum of a file.
+    #
+    # @param [String] path the file path
+    # @param [String] sha1_checksum the checksum of the file
+    #
     def set_sha1_checksums_hash(path, sha1_checksum)
       @sha1_checksums_hash[path] = sha1_checksum
     end
 
+    # Calculates the SHA1 checksum of a file.
+    #
+    # @param [String] path the path to the file
+    # @return [String] the SHA1 checksum
+    #
     def sha1_checksum(path)
       Digest::SHA1.file(path).to_s
     end
 
+    # Test if the OS is Mac OS X.
+    #
+    # @return [Boolean] Whether the OS is Mac OS X
+    #
     def self.mac?
       RbConfig::CONFIG['target_os'] =~ /darwin/i
     end
 
+    # Test if the OS is Linux.
+    #
+    # @return [Boolean] Whether the OS is Linux
+    #
     def self.linux?
       RbConfig::CONFIG['target_os'] =~ /linux/i
     end
 
+    # Test if the OS is Windows.
+    #
+    # @return [Boolean] Whether the OS is Windows
+    #
     def self.windows?
       RbConfig::CONFIG['target_os'] =~ /mswin|mingw/i
     end
diff --git a/lib/guard/listeners/darwin.rb b/lib/guard/listeners/darwin.rb
index 07fafc6..420680b 100644
--- a/lib/guard/listeners/darwin.rb
+++ b/lib/guard/listeners/darwin.rb
@@ -1,41 +1,60 @@
 module Guard
+
+  # Listener implementation for Mac OS X FSEvents.
+  #
   class Darwin < Listener
 
+    # Initialize the Listener.
+    #
     def initialize(*)
       super
       @fsevent = FSEvent.new
     end
 
-    def worker
-      @fsevent
-    end
-
+    # Start the listener.
+    #
     def start
       super
       worker.run
     end
 
+    # Stop the listener.
+    #
     def stop
       super
       worker.stop
     end
 
+    # Check if the listener is usable on the current OS.
+    #
+    # @return [Boolean] whether usable or not
+    #
     def self.usable?
       require 'rb-fsevent'
       if !defined?(FSEvent::VERSION) || (defined?(Gem::Version) &&
           Gem::Version.new(FSEvent::VERSION) < Gem::Version.new('0.4.0'))
-        UI.info "Please update rb-fsevent (>= 0.4.0)"
+        UI.info 'Please update rb-fsevent (>= 0.4.0)'
         false
       else
         true
       end
     rescue LoadError
-      UI.info "Please install rb-fsevent gem for Mac OSX FSEvents support"
+      UI.info 'Please install rb-fsevent gem for Mac OSX FSEvents support'
       false
     end
 
-  private
+    private
 
+    # Get the listener worker.
+    #
+    def worker
+      @fsevent
+    end
+
+    # Watch the given directory for file changes.
+    #
+    # @param [String] directory the directory to watch
+    #
     def watch(directory)
       worker.watch(directory) do |modified_dirs|
         files = modified_files(modified_dirs)
diff --git a/lib/guard/listeners/linux.rb b/lib/guard/listeners/linux.rb
index 68453cb..ba31076 100644
--- a/lib/guard/listeners/linux.rb
+++ b/lib/guard/listeners/linux.rb
@@ -1,6 +1,11 @@
 module Guard
+
+  # Listener implementation for Linux inotify.
+  #
   class Linux < Listener
 
+    # Initialize the Listener.
+    #
     def initialize(*)
       super
       @inotify = INotify::Notifier.new
@@ -8,44 +13,53 @@ module Guard
       @latency = 0.5
     end
 
+    # Start the listener.
+    #
     def start
       @stop = false
       super
       watch_change unless watch_change?
     end
 
+    # Stop the listener.
+    #
     def stop
       super
       @stop = true
       sleep(@latency)
     end
 
+    # Check if the listener is usable on the current OS.
+    #
+    # @return [Boolean] whether usable or not
+    #
     def self.usable?
       require 'rb-inotify'
       if !defined?(INotify::VERSION) || (defined?(Gem::Version) &&
           Gem::Version.new(INotify::VERSION.join('.')) < Gem::Version.new('0.8.5'))
-        UI.info "Please update rb-inotify (>= 0.8.5)"
+        UI.info 'Please update rb-inotify (>= 0.8.5)'
         false
       else
         true
       end
     rescue LoadError
-      UI.info "Please install rb-inotify gem for Linux inotify support"
+      UI.info 'Please install rb-inotify gem for Linux inotify support'
       false
     end
 
-    def watch_change?
-      !!@watch_change
-    end
-
-  private
+    private
 
+    # Get the listener worker.
+    #
     def worker
       @inotify
     end
 
+    # Watch the given directory for file changes.
+    #
+    # @param [String] directory the directory to watch
+    #
     def watch(directory)
-      # The event selection is based on https://github.com/guard/guard/wiki/Analysis-of-inotify-events-for-different-editors
       worker.watch(directory, :recursive, :attrib, :create, :move_self, :close_write) do |event|
         unless event.name == "" # Event on root directory
           @files << event.absolute_name
@@ -54,6 +68,16 @@ module Guard
     rescue Interrupt
     end
 
+    # Test if inotify is watching for changes.
+    #
+    # @return [Boolean] whether inotify is active or not
+    #
+    def watch_change?
+      !!@watch_change
+    end
+
+    # Watch for file system changes.
+    #
     def watch_change
       @watch_change = true
       until @stop
diff --git a/lib/guard/listeners/polling.rb b/lib/guard/listeners/polling.rb
index 894bff9..ffc6508 100644
--- a/lib/guard/listeners/polling.rb
+++ b/lib/guard/listeners/polling.rb
@@ -1,24 +1,46 @@
 module Guard
+
+  # Polling listener that works cross-plattform and
+  # has no dependencies. This is the listener that
+  # uses the most CPU processing power and has higher
+  # File IO that the other implementations.
+  #
   class Polling < Listener
 
+    # Initialize the Listener.
+    #
     def initialize(*)
       super
       @latency = 1.5
     end
 
+    # Start the listener.
+    #
     def start
       @stop = false
       super
       watch_change
     end
 
+    # Stop the listener.
+    #
     def stop
       super
       @stop = true
     end
 
-  private
+    # Watch the given directory for file changes.
+    #
+    # @param [String] directory the directory to watch
+    #
+    def watch(directory)
+      @existing = all_files
+    end
 
+    private
+
+    # Watch for file system changes.
+    #
     def watch_change
       until @stop
         start = Time.now.to_f
@@ -29,9 +51,5 @@ module Guard
       end
     end
 
-    def watch(directory)
-      @existing = all_files
-    end
-
   end
 end
diff --git a/lib/guard/listeners/windows.rb b/lib/guard/listeners/windows.rb
index 1f74d14..f7be41e 100644
--- a/lib/guard/listeners/windows.rb
+++ b/lib/guard/listeners/windows.rb
@@ -1,35 +1,48 @@
 module Guard
+
+  # Listener implementation for Windows fchange.
+  #
   class Windows < Listener
 
+    # Initialize the Listener.
+    #
     def initialize(*)
       super
       @fchange = FChange::Notifier.new
     end
 
+    # Start the listener.
+    #
     def start
       super
       worker.run
     end
 
+    # Stop the listener.
+    #
     def stop
       super
       worker.stop
     end
 
+    # Check if the listener is usable on the current OS.
+    #
+    # @return [Boolean] whether usable or not
+    #
     def self.usable?
       require 'rb-fchange'
       true
     rescue LoadError
-      UI.info "Please install rb-fchange gem for Windows file events support"
+      UI.info 'Please install rb-fchange gem for Windows file events support'
       false
     end
 
-  private
-
-    def worker
-      @fchange
-    end
+    private
 
+    # Watch the given directory for file changes.
+    #
+    # @param [String] directory the directory to watch
+    #
     def watch(directory)
       worker.watch(directory, :all_events, :recursive) do |event|
         paths = [File.expand_path(event.watcher.path)]
@@ -38,5 +51,11 @@ module Guard
       end
     end
 
+    # Get the listener worker.
+    #
+    def worker
+      @fchange
+    end
+
   end
 end
diff --git a/spec/guard/listener_spec.rb b/spec/guard/listener_spec.rb
index 639e761..011b829 100644
--- a/spec/guard/listener_spec.rb
+++ b/spec/guard/listener_spec.rb
@@ -172,7 +172,7 @@ describe Guard::Listener do
 
   describe "#ignore_paths" do
     it "defaults to the default ignore paths" do
-      subject.new.ignore_paths.should == Guard::Listener::DefaultIgnorePaths
+      subject.new.ignore_paths.should == Guard::Listener::DEFAULT_IGNORE_PATHS
     end
 
     it "can be added to via :ignore_paths option" do