Ruby行内注释的代码在运行时被忽略。单行注释＃字符开始，他们从＃到行末如下：
#!/usr/bin/ruby -w # This is a single line comment. puts "Hello, Ruby!"
上述程序执行时，会产生以下结果：
Hello, Ruby!
Ruby的多行注释
可以注释掉多行使用 =begin 和 =end 语法如下:
#!/usr/bin/ruby -w puts "Hello, Ruby!" =begin This is a multiline comment and con spwan as many lines as you like. But =begin and =end should come in the first line only. =end
上述程序执行时，会产生以下结果：
Hello, Ruby!
确保后面的注释是保持足够的距离的代码，能使它很容易区分。如果在一个块中存在一个以上的尾端注释它们对齐。例如：
@counter # keeps track times page has been hit @siteCounter # keeps track of times all pages have been hit