Craigslist is a central network of online communities, featuring free classified advertisements (with jobs, internships, housing, personals, erotic services, for sale/barter/wanted, services, community, gigs, resume, and pets categories) and forums on various topics. The service was founded in 1995 by Craig Newmark for the San Francisco Bay Area. After incorporation as a private for-profit company in 1999, Craigslist expanded into nine more U.S. cities in 2000, four each in 2001 and 2002, and 14 in 2003. As of September 2007, Craigslist had established itself in approximately 450 cities in 50 countries. As of 2007, Craigslist operates with a staff of 24 people. Its sole source of revenue is paid job ads in select cities ($75 per ad for the San Francisco Bay Area; $25 per ad for New York, Los Angeles, San Diego, Boston, Seattle, Washington D.C., Chicago and recently Portland, Oregon) and paid broker apartment listings in New York City ($10 per ad).