What makes a page accessible? In order to better reach our diverse audience, it helps to understand the challenges faced by those who access our designs and content.

Connection Speed
People with dial-up connections may not be able to access large files like PDFs or large graphics. The loading time for your page is measured from the first click to the appearance of the final bit of text or the last graphic. Seven seconds is about how long people will wait for the page to download. If it takes much longer, a good search engine will find them another, faster route to the information they seek.

Remember that although a page loads quickly on the machine at work, load time will be considerably slower over a dial-up connection. Optimize your graphics (none should be over 72 dpi), offer html as well as PDF versions of large documents.

Mobility Impairments
Many people in our audience have impaired motor skills.
These impairments can be caused by arthritis, diseases such as multiple sclerosis, or Parkinson's, by stroke or other brain injury, or even by repetitive stress injuries. These impairments can make it difficult or impossible to use a standard keyboard or mouse, or to press more than one key at a time.

Visual Impairments
Ranging from near- or farsightedness, colorblindness, inability to distinguish subtle contrast to blindness, visual impairments influence how your audience sees your page. Many people with visual impairments use text readers, large screens or other devices to access the web. Contrast of text with background, use of color in graphics and activities requiring precise hand-eye coordination need to be given extra attention. Use of audible as well as visual information may make the site more accessible.

It is important to note that one of the first age-related impairments affecting our audience is the deterioration of eyesight, specifically, a loss of ability to discern contrast and color. Use of high contrast colors to convey information is a must.

Hearing Impairments
Again, people who have hearing impairments may be unable to hear sound, able to hear some sound, or have difficulty distinguishing specific sounds when there is background noise. Use visual as well as audible prompts.

Cognitive Impairments
People with cognitive impairments may have difficulty solving problems, recognizing patterns or using language. They may also have difficulty remembering details. Poorly organized or inconsistent navigation schemes may be confusing. It is also important to note that people with seizure disorders such as epilepsy may be affected by web site design, as flashing or shifting light or repetitive sound patterns may trigger seizure.

Find out more. Check the links section of this page for more information about the barriers to web access.

Last Update: September 2006

Your Role as Author:
Now What?

Tips and Best Practices
Our Best Work

"The Minimum"
What needs to be done?

Primary Barriers to Access
More than Bandwidth

Universal Design
It's the Right Thing to Do

Fun With ALT Text
Avoiding ALT="pitfalls"

Test Your Accessibility
Tools and Tips

Links to
Primary Sources

Back to
NPS 508 Home

Back to
NPS HelpDesk