Skip Navigation Bar

National Library of Medicine Web Pages & Accessibility

The National Library of Medicine (NLM) is committed to serving the entire public, and that means striving to ensure that all pages of our site are accessible to the greatest possible number of people and Assistive Technology devices.

Education and Compliance

The following links can help you develop pages that comply with accessibility laws and guidelines:

Health and Human Services (HHS) Web Policies & Standards
Policies and standards from the Web and Communication and New Media Division at HHS including the HHS Section 508 Accessibility Policy and Section 508 Checklist. Additional information is available from the NIH Web Authors Group.

Section 508
Guidelines from the Access Board Electronic & Information Technology including points (a) through (p) of Subsection 1194.22 Web-based intranet and internet information and systems. Additional standards may apply depending on the type of development (e.g. software applications or videos).

Additional Resources

Web Accessibility Initiative (WAI)
Web Content Accessibility Guidelines 2.0 outlines the industry standards developed by the WAI, part of the World Wide Web Consortium (W3C). Information about Evaluation Tools is available for Web content developers and Web users who wish to make the Web more accessible.

Web Accessibility in Mind (WebAIM)
Articles about Web accessibility including user perspectives, HTML, Adobe Acrobat PDFs, images, and captioning. There is also a Section 508 Checklist for HTML.

Accessibility and Web Standards

In order to design sites that are accessible and that work well in several browsers, NLM pages must:

  • Include accessibility planning from the beginning of the project to avoid costly retrofitting and project delays.
  • Meet the XHTML 1.0 Transitional standard, including the DOCTYPE and XML namespace declaration described on our XHTML Guidelines page.
  • Structure content in a logical order that can be maintained when the style sheet is disabled.
  • Provide text equivalents for all non-text elements (i.e., images, animations, audio, video). All videos must include captioning.
  • Provide alternative content for features (e.g., applets or plug-ins) that may not be supported.
  • Provide summaries of graphs and charts.
  • Ensure that all information conveyed with color is also available without color.
  • Identify changes in the natural language of a document's text and any text equivalents (e.g., captions) of non-text content.
  • Ensure that data tables are constructed so that a user accessing the site with a screen reader or other assistive technology is presented with content in a logical order.
  • Ensure that tabbing order flows logically across all pages including forms. That is to say that if a user is tabbing rather than clicking through our site, her progress through the site is logical.
  • Avoid invisible spacer GIFs and similar visual objects that do not convey meaning.
  • Avoid using tables for layout purposes or as a design tool. For instance, this page uses no HTML tables, and it works in a browser such as Netscape 4.7, although the layout is somewhat degraded in that browser.
  • Ensure Web pages work in a variety of Web browsers and assistive technologies (i.e. screen readers).

In addition, all XHTML and Style Sheets must validate.

If you have questions about accessibility, contact the Web and Information Management Unit.