Use of web standards set by the W3C is ideal for optimal web accessibility. Use of semantic HTML markup is critical, as it provides meaning to the various sections of your pages. This includes:

• Use of layout elements appropriate for content, such as NAV elements for menus, ARTICLE elements for page content, and ASIDE elements for supplementary page content such as recommended links or author biographies.
• Use of descriptive names to element classes and IDs. Instead of labelling a sidebar DIV or ASIDE element "left", label it "sidebar".
• Use of classes instead of IDs for elements that are used more than once on a page.
• Use of the ALT attribute for all images.

If you need further assistance with understanding and using semantic HTML in your page markup, consult your web team or a development agency like Soshal.