In HTML you can write comments.  

HTML Comments Syntax

Attributes are provided with start tag of HTML element.

Start tag Element content End tag
<!-- Comments -->


Sample Code

<!-- Text inside these will be treated as comments -->


Attributes    Blocks    Color-Values    Colornames    Colors    Comments    CSS    Editors-for-writing-html    Elements    Entities    Formatting-in-HTML    Forms    Head    Headings    HTML-Reference    IFrames    Image    Javascript    Layouts    Links    Options for building websites    Paragraphs    pointers and questions    Symbol-for-Mathmatics    Symbol-for-Punctuations    Symbols    Tables    Whats-new-in-HTML5