HJSplit is a popular freeware program to split and recombine files. The program is available on Windows, Linux and a variety of other platforms. Why should one want to split and recombine files? For instance, think of a file of 50 Mb, and try to send it to a friend, post it in a newsgroup or upload it to a Website or FTP server. It is usually easier to send/receive, upload/download smaller parts than handle the entire file in one go.