This screen shot provided by Yahoo Inc., shows its upgraded e-mail with slide-show feature. Yahoo Inc. is sprucing up its free e-mail service in the latest attempt to persuade people to spend more time on its website. (AP Photo/Yahoo Inc.) NO SALES

(AP) -- Yahoo Inc. is sprucing up its free e-mail service in the latest attempt to persuade people to spend more time on its website.

The new look debuting Wednesday includes several new features and repackages some previously introduced tools that hadn't been easy to find or use.

considers it to be the biggest overhaul of its e-mail service in five years. As part of the redesign, Yahoo is promising its e-mail will run twice as fast as it has been.

Yahoo's estimated 273 million worldwide e-mail users will have the choice to switch to the new look beginning Wednesday, in a testing period that will last through at least the rest of the year. All e-mail accounts will automatically be converted to the new format at a still-undetermined time next year.

In a long-promised change, Yahoo is finally offering its e-mail users the opportunity to connect their e-mail accounts with their profiles on Twitter's popular short-messaging service. The addition means people will be able to see incoming Twitter messages and post their own musings, or "tweets," directly from their Yahoo e-mail. Yahoo previously had added a similar tool that connected its e-mail service with accounts.

Another upgrade will enable Yahoo's e-mail users to play videos and peruse pictures sent to them without having to follow links to a new page. Both Corp. and Google Inc. have already included some of this technology in their own free e-mail services.

Yahoo also is adding a pane on the left-hand side of the inbox that aims to make some common tasks easier, such as finding top contacts or searching for material contained within e-mails.

The e-mail facelift comes at a time when Yahoo has been losing luster with millions of Web surfers, many of whom are communicating with each other more in online forums such as Facebook and Twitter, or gravitating to . The migration has made it more difficult for Yahoo to sell advertising, a factor that has had been hurting its stock price for the past two years.

The number of Yahoo e-mail users was 10 percent lower in September than a year ago, according to the latest data from the research firm comScore Inc. That ranked Yahoo as the world's second largest Web-based e-mail service behind Microsoft's rival offering. Microsoft's total users have dipped 3 percent during the past year to 362 million. Google's Gmail has climbed 21 percent during the past year to 193 million worldwide users.

Cultivating loyal e-mail users is important because they tend to be frequent visitors and they often remain logged in when using other online services run by the e-mail providers. The return trips and logged-in activity creates more opportunities to show ads.