Proxy servers act as intermediaries for requests from clients to access resources from other servers. They can be used to share an internet connection on a local area network when multiple computers need access. Proxy servers also cache requests to speed up internet surfing for clients and can hide a client's IP address for anonymity and security reasons. Private proxies are exclusively used by one client to hide their public IP address, while shared proxies have multiple users accessing the same server and can transmit large amounts of data in a cost effective manner.