SAN FRANCISCO (AP) – Yahoo Inc. will introduce new features Monday for its popular Web-based e-mail program, including software that allows computer users to type text messages on a keyboard and send them directly to someone’s cell phone.

The enhancements make it easier to send e-mail, instant messages or text messages from a single Web site – no need to launch or toggle between separate applications or devices. It will take up to six weeks for all the new features to become available to all 254 million Yahoo Mail subscribers in 21 languages worldwide.

The most obvious beneficiaries will be parents, who will be able to use their keyboards to type messages sent to their children’s cell phones – no thumb-twisting typing on a dial pad, said Yahoo Vice President John Kremer.

”We’re giving you the right way to connect at the right time with right person,” said Kremer, whose two preteen sons vastly prefer text and instant messages to e-mail.

The changes come amid fierce competition among providers of free, Web-based e-mail services. Yahoo and Microsoft Corp.’s Hotmail have long dominated the niche, but Google Inc.’s Gmail has grown quickly since its introduction in April 2004.

In February, Yahoo announced that it would provide unlimited storage space, and earlier this month Redmond, Washington-based Microsoft said Hotmail would increase free storage from 2 to 5 gigabytes. Time Warner Inc.’s AOL, the fourth largest e-mail provider, began offering unlimited storage last summer. Google provides nearly 3 gigabytes.

Sunnyvale-based Yahoo bills the changes as the most significant overhaul of Yahoo Mail since its launch in 1997. The new version replaces a one-year-old beta program and adds new features, including text messaging, a more comprehensive e-mail search engine and an easier to read and edit contacts database.

Users who do not want the upgrades – or whose computers are too slow to handle them – can opt to remain with the current version, which Yahoo will call ”Classic.”

The new version allows users to click on a contact and then select whether to send that person an e-mail, instant message or text message. You could send an e-mail or instant message if you know the recipient is at the computer – or a text message if the recipient is on the road with a cell phone.

”This gives people the ability to reach anybody in their contact database anytime,” said Mike McGuire, vice president of research at industry analysis firm Gartner Inc. ”For good or evil, it’s going to be much easier for anybody to get a hold of you.”