Depending on the ISP that you use for your broadband Internet connection, you may be subject to limitations on your bandwidth usage and connection speed. This varies among ISPs as well as types of connection.
Most DSL subscribers do not run into bandwidth limiting policies. Because DSL users have dedicated connections, they don't face the same problem as cable customers on crowded networks.
However, your DSL or cable ISP may place limits on upstream bandwidth and specifically prohibit your running a Web, file, or game server. This has become more of an issue as peer-to-peer file sharing networks become more popular. They also may place restrictions on customers reselling service or providing service to an entire network with a single subscriber account.
If you have a satellite Internet connection or connect through a campus network, you may be subject to a fair access policy. A fair access policy limits the amount of bandwidth any user may use in a given period. When a user exceeds their allotted amount of bandwidth, the ISP may restrict his usage for a short time. Activities like normal Web surfing use little bandwidth and are unlikely to exceed fair access limits. The bandwidth thresholds for a fair access policy vary between ISPs so you should examine your contract carefully.