Generally, any networking technology that controls the amount of network bandwidth used by servers, applications, or network communication paths.
In the context of Microsoft Internet Information Services (IIS), for example, bandwidth throttling is a technique for controlling the amount of network bandwidth used by individual Web sites hosted on the server. Bandwidth throttling can be used to prevent hits on a popular site from overwhelming the server and preventing other sites hosted on the server from being accessed by clients.
For example, if five Web sites are being hosted on a single machine running IIS but one of them is extremely popular, the other sites might get starved for bandwidth and users might have difficulty connecting to them.
In order to rectify this situation, a specific maximum bandwidth level can be allocated to the popular site with the Internet Services Manager snap-in used for administering IIS using the Microsoft Management Console (MMC).
If this maximum bandwidth is exceeded, no further connections to that site are allowed until the bandwidth utilization level drops below the threshold. This allows the unallocated bandwidth to be shared among the remaining less popular sites so that users can connect to them.