An internet service provider (ISP) is a company that offers individuals and businesses access to the Internet. ISPs connect users to the web through various technologies, such as fiber optics, cable, or DSL. They may also provide additional services like email accounts and web hosting. ISPs can be categorized into different types, including dial-up, broadband, and satellite providers. The choice of an ISP often depends on factors like speed, reliability, and cost. Popular ISPs include Comcast, AT&T, and Verizon, each offering various plans to meet customer needs.