Only recently a small private start-up, LinkedIn has quickly become a major player in the social networking sphere—growing on the New York Stock Exchange, expanding its offices around the world and adding interactive features that align it with sites such as Facebook.

Now a 120 million-member social network, the Mountain View-based site will host a town hall Monday with President Obama at the Computer History Museum. "Putting America Back to Work: LinkedIn Presents a Town Hall with President Obama," will feature a Q&A with Obama about job creation from a live audience.

LinkedIn’s Evolution

The 8-year-old website has gone from being a static profile to a dynamic social network, according to online marketing professional Lana Goldenberg.

"The site has added many more features, such as a news feed," said Goldenberg, who advises businesses on how to rein in clients through the site.

It’s how Stanford graduate Alex Medearis, 26, was recruited for his job. "Software engineers often get requests through the site," he said.

For Palo Alto resident, Clarence Hu, 33, a LinkedIn profile is a business card for young professionals, especially in Silicon Valley.

“Every young person I know uses LinkedIn,” said Hu, a Stanford graduate who majored in computer science. “Now people lack credibility if they don’t have a profile.”

Still, said Medearis, the site carves out a niche for professional purposes but is not the best tool for socializing online. “I have much more of an online social life through Facebook,” he said.

Linkedin has experienced steady growth over the past year. On May 19, the company went public on the New York Stock Exchange. Eager investors took note, and the company’s stocks rose by 109 percent to a $94.25-a-share closing price.

By July, it had surpassed Myspace as the No. 2 social network in the U.S. On Aug. 4, it became the world's largest social networking site, with membership in more 200 countries and offices in almost 20 countries.

It's not surprising, then, that more than half of the site's membership is outside of the U.S. In June, it surpassed 10 million members in India. On Thursday, it passed 1 million members in Belgium, and just opened an office in Munich, Germany. There are now 6 million members in the UK, and two million each in Spain, Italy, and the Netherlands.

You’re On LinkedIn. Now What?

With the site’s growth, it’s important to have a complete profile, advised Goldenberg. “Be sure to put keywords of how you want to be found in the headlines. It only takes a few minutes to update,” said Goldenberg, who grew up in San Jose and now lives in Los Angeles.

She also urges her people to ask for recommendations on the site, as those with more turn up in the search faster, she said. A photo is also “a great way to humanize your profile,” said Goldenberg. “It’s almost like meeting face to face. The profile isn’t complete without one.”

Those with a picture are seven times more likely to have viewers, said Krista Canfield, a senior PR manager at LinkedIn. Furthermore, people with up-to-date profiles are 12 times more likely to be viewed than those with only one position listed.

People should not only list jobs, advised Canfield, but also skills, such as languages, or classes in which they received a certification. The site recently added a feature for people to add "Volunteer Experience and Causes" as well. 

Canfield urged users to branch out and make contacts with those outside of their “comfort zone,” she wrote. But Canfield advised job seekers to network wisely.

"A 'gimme-gimme' mentality is a surefire way to lose professionals' contacts and get deleted from people's networks,” she wrote in an email. “Instead, make sure you take the time to help others in your network, not because you're expecting something in return, but because you truly want them to succeed.”