Having a usable website should be the top priority of anyone who has a site. But there are plenty of things people do that make a website more difficult, or even impossible, to use. Read on for a few of the more common mistakes.

1. Inadequate Search Functionality

If your site consists of more than just a few pages, you need to have a search function to make it easier for visitors to find what they're looking for. The search engine you choose to power it needs to work well and provide complete results in a logical fashion. A search function that doesn't work well and doesn't give complete results will quickly be abandoned (possibly along with your site as a resource).

2. Making Your Site Illegible

Illegibility can happen for a number of reasons. One of the most common is font size. A font that's too small can make reading anything on your site cumbersome at best and impossible at worst. Make sure the fonts on your site are resizable (by using EM-sized fonts instead of pixels), too. Contrast between the background (whether it's a single color or an image) and the type needs to make reading the type easier, not harder. Don't use colors that are opposite each other on the color wheel (green and red, blue and orange, purple and yellow, etc.) right next to each other or the type will be impossible to read.

3. Bad Form Design

Forms need to be short and easy to fill out. Make sure required fields are marked. Make sure any requirements for particular fields (such as password format) are clearly stated to prevent frustration. And make sure that when the form is submitted, something indicates that it was done successfully or not.

4. Making Un-clickable "Links"

No text on your site should be underlined unless it's a link. People expect underlined type to be linked to something, and if it's not, it's frustrating.

5. Browser Incompatibility

There's no excuse for your site not to be compatible (or at least usable) from the major browsers: Internet Explorer, Firefox, and Safari. Firefox and Safari are gaining significant market share, and making your site so it only works in Internet Explorer can mean you exclude up to 30% of Internet users.

6. Inconsistent Navigation

You site's navigation needs to remain consistent across the entire site. This means links to different areas should appear in the same place and in the same order no matter where on your site a visitor is. Links need to be consistently formatted across pages.

7. Unscannable Content

The web was made for scanning content. Using lists, bullet points, numbers, headings, and short paragraphs makes your content easier to read and scan by visitors. Use headings and subheadings to indicate important sections and make use of formatted lists wherever appropriate.

8. No Contact Information

This is a big problem for a lot of sites. Don't hide your contact information. Either provide a form for visitors to fill out to contact you or include your email address and/or phone number in an easy-to-find place. Not including contact information can make users uneasy (especially on a business site) and less likely to do business with you. It's fine to make your email address non-linked or hidden with JavaScript to prevent spam, but make sure regular visitors can still see it.