ZIP: A very popular data compression format. Files that have been compressed with the ZIP format are called ZIP files and usually end with a.ZIP extension. This is a very old archive type and is supported on virtually on all computer and operating systems. The compression strength is by now considered weak.

JAR: Short for Java Archive, a file format used to bundle all components required by a Java applet. JAR files simplify the downloading of applets since all the components (.class files, images, sounds, etc.) can be packaged into a single file. In addition, JAR supports data compression, which further decreases download times.

By convention, JAR files end with a .jar extension. JAR archives are virtually identical to ZIP archives.

CAB: The archive type developed in 1997 by Microsoft. Provides good compression ratios and very fast extraction speeds. Until recently, CAB was the strongest compression available; however upgrades to the RAR, ACE and 7-ZIP formats have dethroned CAB as the strongest compression format.

TAR: Short for tape archive, a UNIX utility that combines a group of files into a single file. The resulting file has a .tar extension.

The tar command does not compress files, but just packs them into a single file for further compression. Frequently, therefore, a tar file is compressed with the compress or gzip commands to create a file with a .tar.gz or .tar.Z extension. These are comparable to ZIP files. Most Windows ZIP utilities can handle this file format.

In Alpha ZIP, you can create a .tar.gz file at once.

LHA: The filename extension for a file produced by the shareware compression and archive software LHARC. The term is also used for a compression program for MS-DOS. The output files have the extension ".lhz".

LHZ: LHA Compressed Archive File. Compressed files using the DOS compression program LHA.

7-ZIP: This is a new file format, that provides better compression than any other existing format. Files compressed in this format have the extension .7z.

Not all compression utilities support the 7-ZIP format. If you are sending files in this format to other people, you have to tell them to use Alpha ZIP or another compatible compression utility to open the file.