sentence: All users can send and receive tweets using the Twitter website.
sentences_after: They can also use other applications that work with Twitter on smartphones. Using Twitter is free, but sending or getting tweets by SMS may cost money. The website is based in San Francisco, California. Twitter also has servers and offices in San Antonio, Texas and Boston, Massachusetts, and soon in Salt Lake City, Utah.
concept_name: user
headings: Twitter
categories: 2006 establishments San Francisco, California Social networking