SAN FRANCISCO — Yahoo Inc. is preparing to introduce a new service that blends several of its website's popular features with two of the Internet's fastest growing activities — blogging and social networking.

The hybrid service, called "Yahoo 360," won't be available until March 29, but the Sunnyvale-based company decided to announce the product late Tuesday after details were leaked to news outlets.

Yahoo is testing the service with a small group of employees, some of whom have been working on the project since last year when the product was operating under the code name "Mingle."

The service is designed to enable Yahoo's 165 million registered users to pull content from the website's discussion groups, on-line photo albums and review section to plug into their own Web logs, or blogs, the Internet shorthand used to describe on-line personal journals.

Yahoo also is making it easier for the service's users to connect with others who share common interests and friends — a practice known as social networking. Participants can either choose to open their blogs to the entire world or restrict access to people invited through e-mail.

"We heard from people that they have a strong desire to stay close to the people who are important to them, but at the same time they didn't want to feel like they were exposing themselves on-line," said Julie Herendeen, Yahoo's vice-president of network products.

The service represents Yahoo's effort to tap into the popularity of blogs and social networking sites.

Although many critics continue to dismiss blogs as mostly prosaic rambling, 27 per cent of on-line adults in the United States read them and another 7 per cent write them, according to a study by the Pew Internet and American Life Project.

Blogs also have gained more credibility as they have broken news missed by the mainstream media and provided firsthand accounts of the war in Iraq and the tsunami that killed thousands in Asia.

Meanwhile, social networking sites are establishing themselves as major on-line attractions.

MySpace.com, the most popular among the bunch, drew 8.9 million unique visitors who generated 4.6 billion page views last month, according to comScore Media Metrix, a research firm. By comparison, Yahoo's 110 million unique visitors accounted for nearly 30-billion page views last month, Media Metrix said

Expanding into social networking and blogging mark another significant step in Yahoo's push to make its website even more essential to the personal and professional pursuits of its users.

The service is also meant to encourage Yahoo's most frequent visitors to create and share more content, a process the company hopes will attract even more people to its site. If it can increase its audience's size and give visitors more reasons to stick around longer, Yahoo would become an even more attractive marketing vehicle for advertisers.

Some of Yahoo's other rivals already have ventured into blogging and social networking, with limited success so far.

On-line search engine leader Google Inc., Microsoft's MSN.com and Ask Jeeves Inc. all have become involved in the blogging movement. Google also is dabbling with a social networking service called Orkut, joining other well-known sites such as Lycos.

MySpace.com Chief Executive Chris DeWolf predicted Yahoo will have a tough time catching up with entrenched social networking sites like the one he runs.

Yahoo is entering social networking with a significant advantage because so many people have already shared their personal information with the company to become registered users. Yahoo also has deep pockets, with $3.5-billion in cash and short-term investments at the end of 2004.

When it becomes available later this month, Yahoo 360 initially will be restricted to users invited by the company. Those early participants will then be able to invite others.