Usability is critical to your site's success because as well as exploring how well Internet users can use and move around the website, it ultimately affects the number of return visits or referrals to your site and, if you sell on-line, your profits.

Sites that are difficult to navigate are a turn off. Research shows that users leave websites if they get lost, or if it takes too many clicks to find what they want, or if their questions aren't answered.

However, 7 out of 10 users return to sites that are easy to use

Remember: visitors to your site are on a mission: they're looking for information, to buy goods, locate a supplier. If their progress is blocked or too slow, they'll quickly go elsewhere.

But make it a good experience, and they'll return.

Five key points to improve usability:

1. Learnability

How easy and how long does it take to perform and learn core tasks? For example, if you run a travel business, how simple is it to book a holiday?

2. Efficiency

Does your website allow users to carry out their goals? For example, find the information they need, or buy goods and services in an quick, organized way? Can they quickly find your telephone number or postcode?

3. Utility

Does your website allow the user to do what they want to do? This point is all about functionality. Users may be searching for a new car but if they can't specify petrol or diesel, a small runaround or a SUV, they'll find a rival site that works.

4. Memorability

Users have to learn how to use your website and remember the various processes next time they visit. Consistent design elements aid memory, so if navigation is on the left on the home page, don't move it around!

Not sure where to put sections and pages? Get friends, family, colleagues or clients to help. Write each topic on a card and ask them to place them in appropriate categories. You may be surprised!

5. Effectiveness

Once your users have learned how to use the website, how productive is their stay? Effectiveness = quickly+ easily.

The only way to find this out is through usability testing. Again, ask a small group of users to help. Give them a set of tasks such as find the price of a product, locate the company's email details, check availability/locations. Review how they get on... and act on it.