Internet Explorer, which had almost 80 percent of users in November 2007, lost ground to Chrome among desktop computer users and Safari for mobile devices, according to data from Net Applications, an analytics and Web applications company based in Aliso Viejo, California.

Microsoft, based in Redmond, Washington, has been slower to update the browser in an increasingly competitive market, said Vincent Vizzaccaro, who directs marketing at Net Applications.

“Microsoft has to worry about its enterprise customers, and you see a much longer cycle for testing and deployment,” he said.

Chrome’s share of desktop users climbed to 17.6 percent from 10.4 percent at the end of last year, as Mountain View, California-based Google advertised the browser on its sites. Safari, from Cupertino, California-based Apple, had a 62.2 percent share among mobile users, compared with 49.2 percent in December.

Internet Explorer remained the leading browser among desktop and mobile users, with a share of 49.6 percent last month. Mozilla’s Firefox, once the largest competitor to Internet Explorer and still the top desktop alternative, is ceding market share to Chrome. Firefox had 21.2 percent of all browser users, after reaching 24.6 percent in April 2010, the data show.

“The browser industry has shifted over the past few years -- this is a natural evolution that has led to healthy competition and strong progress across the Web while benefiting customers,” said Roger Capriotti, director of Internet Explorer product marketing, in an e-mailed statement.

Microsoft has been trying to get people to use Internet Explorer 9 instead of older versions, he said.