Craigslist began as a local community newsletter in San Francisco and has grown to become one of the most visited English websites worldwide, hosting classified ads across over 450 cities. It focuses on specific local communities, originally just San Francisco before expanding to other major US cities. While starting as a personal project, Craigslist incorporated in 1999 and has continued growing each year to more cities as a profitable business, though it faces ongoing challenges removing scam posts from its sites.