Text Fonts and Colors

• Choose fonts that are easy to read for users with low vision. Don't rely on color alone to convey information. When possible, text should use sans-serif fonts, such as Verdana and Arial. These are easier to read on a computer screen than fonts with serifs.
• All information that is conveyed with color should also be available without color.
• Choose colors that can be distinguished by people who are colorblind. Use Vischeck to see how your web page appears to users with colorblindness.
• When choosing backgrounds and colors, make sure that color combinations are easy on the eyes. 
• Don't use background images that blend in with overlaid text. It may not be noticeable to users with good eyesight, but this can make your web page hard to read for users with low vision.

Graphics and Multimedia

• Non-text materials cannot be read by screen readers. Use an ALT tag to provide a text description of all non-text items.  
• Provide equivalent alternatives for any multimedia presentation and synchronize these alternatives with the presentation, such as a text transcript with audio materials and closed-captioning for video materials.
• People with photosensitive epilepsy can have seizures triggered by flickering or flashing in the 4 to 59 flashes per second (Hertz) range with a peak sensitivity at 20 flashes per second as well as quick changes from dark to light (like strobe lights). If you include animated .gif images or other refreshing content that cause the screen to flicker, avoid causing a flicker with a frequency greater than 2 Hertz and lower than 55 Hertz.

Image Maps

• Image maps fall into two categories: server-side image maps and client-side image maps.
• Navigating image maps can present problems. Provide textual alternatives.
• A client-side image map's functions are provided on the client's (the user's browser) end rather than at your web server's side. All the information needed to run the map is included in your web page document. Since text-only browsers, screen readers, or assistive devices may not be capable of interpreting links in server-side image maps, use client-side image maps instead of server-side image maps.
• Server-side image maps do not allow you to use ALT tags to describe individual links in the image map. So if you use a server-side image map, provide a redundant set of text links to duplicate the links in the map. This allows users to interact with the links without having to use a pointing device, such as a mouse.

Tables

• If you use a table for layout purposes, make sure the table makes sense when it is linearized. This means that the cells are read in the order in which they appear in the HTML source code. This is not necessarily the order in which the text is laid out on the screen.
• Provide row and column headers on data tables using the TH tag
• For data tables that have two or more logical levels of row or column headers, use appropriate markup to identify those divisions.

Frames

• To facilitate frame identification and navigation and to minimize confusion for screen reader users, title each frame, use the HTML "title" attribute.
• Use the NOFRAMES tag to define frames content for browsers that can't display frames.

Style Sheets

• Style sheets are used to control the layout and appearance of web pages. Screen readers ignore style sheets when reading the content to users. If you use a style sheet, check your page with styles turned off to see if the page still makes sense.
• How to turn off style sheets in your browser:
  Microsoft Internet Explorer: Tools, Internet Options, Accessibility, Check all boxes under "Formatting"
  Netscape Navigator: Edit, Preferences, Advanced, Uncheck "Enable style sheets"

Scripts, Applets, PDF Files, and Other Applications

• Provide alternative content for users with browsers that don't support scripts. Put the content within a noscript tag.
• If your web page requires the user to have an applet, plug-in, or other application to interpret the page's content, you must provide a link on the page to it.
• Adobe PDF (Portable Data Format) files can be interpreted as graphics rather than as text by screen readers, rendering them inaccessible. If you must include a PDF file, make an HTML version of the file and include a links to both versions.
• Include ALT tags when you use Java applets so browsers that don't support Java will give the user information about the applet's function.

Interactivity

• Electronic forms that are supposed to be completed online should allow people using assistive technology to complete the forms. They should be able to access the information, field elements, and functionality required for completion and submission of the form, including all directions and cues.
• If a timed response is required, alert the user. Provide a way for the user to indicate if they need more time to respond.
• Screen readers are unable to read moving text. Make sure that moving, blinking, scrolling, or auto-updating objects or pages can be paused or stopped.

Navigation

• Navigation links, menus, or banners are often repeated on each web page. Include a "skip to main content" link at the top of each page so that screen reader users can save time and don't have to listen to a repeated menu each time they move to a new web page.
• At the top of each page, include an invisible "skip to main content" link by using a tiny image that is the same color as the background with ALT text = "skip to main content." The link should take users to the top of the content section of the page.

Text-Only Page

• If you cannot accomplish compliance with these guidelines in any way on your web page, you must still provide users with disabilities with the equivalent information or functionality. This can be done with a text-only page.
• The content of the text-only page must be updated whenever the primary page changes. By choosing to offer a text-only version of your web pages, you will have two versions of your website to maintain and update.
• Put the link to your text-only version in the upper left-hand corner of your main web page. This will make the link the first thing that a screen reader will read.