The cURL libraries provide a nice interface for file transfers to and from a webserver. They have support for a wide variety of protocols (like HTTPS) giving them an edge over built-in PHP functions like fsockopen(). The libraries are thread-safe, IPv6 compatible, and will work with any technology that is built on top of HTTP. Whether you are building simple script to fetch a web page, or a secure payment gateway, leveraging the functions built into cURL can save a lot of time. Definition: cURL stands for "Client URLs", and was developed by Daniel Stenberg in 1998 as a command line tool. libcurl is a portable library that provides an easy interface to the cURL functionality. Both cURL and libcurl can transfer files using a wide variety of protocols, including HTTP, HTTPS, FTP, FTPS, GOPHER, LDAP, DICT, TELNET and FILE. The cURL libraries are truly open source, with an MIT/X derivative license. Installation: From PHP version 4.2.3 on, you need a cURL version of at least 7.9.0....