Plaxo is an online address book

Address book

An address book or a name and address book is a book or a database used for storing entries called contacts. Each contact entry usually consists of a few standard fields...

 and social networking service originally founded by Sean Parker

Sean Parker

Sean Parker is an American technology businessman and entrepreneur. He co-founded Napster, Plaxo, Causes, and Airtime, and was Facebook's founding president. His net worth is estimated at $2.1 billion.-Early life:...

, Minh Nguyen and two Stanford engineering students, Todd Masonis and Cameron Ring. Plaxo, based in Sunnyvale, California

Sunnyvale, California

Sunnyvale is a city in Santa Clara County, California, United States. It is one of the major cities that make up the Silicon Valley located in the San Francisco Bay Area...

, is a subsidiary of cable television company, Comcast

Comcast

Comcast Corporation is the largest cable operator, home Internet service provider, and fourth largest home telephone service provider in the United States, providing cable television, broadband Internet, and telephone service to both residential and commercial customers in 39 states and the...

.
The company launched on November 12, 2002, and was funded by venture capital

Venture capital

Venture capital is financial capital provided to early-stage, high-potential, high risk, growth startup companies. The venture capital fund makes money by owning equity in the companies it invests in, which usually have a novel technology or business model in high technology industries, such as...

 including funds from Sequoia Capital

Sequoia Capital

Sequoia Capital is a Californian venture capital firm located on Sand Hill Road in Menlo Park, California. The Wall Street Journal has called Sequoia Capital "one of the highest-caliber venture firms", and noted that it is "one of Silicon Valley's most influential venture-capital firms"...

. Plaxo announced May 14, 2008, that it had signed an agreement to be acquired by Comcast.