- The first layer of a web page is the markup.
- The markup language used is HTML.
- The current version is 5.
Currently there are efforts to develop a standard to allow for customized HTML tags: Web Components.
- The second layer of a web page is the presentation.
- The language used for presentation is CSS.
- The current version is 3.
A useful extension to plain CSS is Sass.
- The third layer of a web page is the behaviour.