File extensions

File Extensions

A file extension or file name extension is the ending of a file that helps identify the type of file in operating systems, such as Microsoft Windows. In Microsoft Windows, the file name extension is a period that is often followed by three characters, but may also be one, two, or four characters long. For example, the file name "myfile.txt" has a file extension of ".txt", which is a file name extension associated with text files.

File Compression

If you download many programs and files off the Internet, you've probably encountered ZIP files before. File compression system makes this easier, especially for Web users, because it lets you reduce the overall number of bits and bytes in a file so it can be moved faster over slower Internet connections, or take up less space on a disk. Once you download the file, your computer uses a program such as Win-zip or Stuff-it to expand the file back to its original size. If everything works correctly, the expanded file is the same to the original file before it was compressed.