This chapter summarizes research that the Pew Internet and American Life project has been conducting since 2000, in particular describing the diffusion of the Internet in terms of both users and domains of use. Internet use is still growing, although growth is slowing as a large proportion of the US population already has access. By the end of 2003, approximately two-thirds of adults in the United States used the Internet at least occasionally, with most logging in from home. The Pew project paints a detailed description of the domains in which people use the Internet: developing and maintaining social ties, seeking health-care information for themselves and those for whom they care, maintaining involvement in national and local civic issues, seeking government information and services, searching for product information and making commercial transactions, and creating content that others can read and download.