Nine months ago, when Nielsen Net/Ratings considered that the FireFox website has enough traffic to be taken into consideration, there were few to suspect that the browser will become Internet Explorer's nightmare.

It seems the users' wish to have an alternative browser is so strong that only in March FireFox's website was visited by 2.6 million users among which 71% men and 29% women.

Nielsen Net/Ratings didn't offer any appraisal of the number of users who downloaded the browser. In February the number of visitors was 2.2 million users, and in January 1.6 millions.

Last year, when Nielsen Net/Ratings started to monitor the FireFox website, the number of visitors had reached 794,000, which means the site's traffic grew with 237%.

FireFox's market share has reached 5% and the monthly increase rate is still 0.5%. Internet Explorer continues to have 90% of the browser market, but Microsoft is seriously concerned about Firefox's threat. The company is putting all its hopes into Internet Explorer 7.0 to regain the prestige of the browser.

According to Nielsen Net/Ratings, the reasons why FireFox is so successful are: stability, pop-up blocking ability and the possibility of browsing on several sites in the same window.

The increasing popularity of the browser is giving web designers a rough time, because they have to make sure that the sites are compatible with it.