What is an Archive?

Archives are files that contain other files. Typically the files in an archive are compressed, but does not have to be. Archives usually have file names ending with ZIP, ZIPX, LZH, LHA, GZ, or CAB, depending on how they were created. Archives make it easy to group files and make transporting and copying these files faster.

An archive typically contains file that are not used often. For example you might backup your old computer files into an archive for safe storage. It’s like packing household items into boxes with labels and storing them in your garage. You might want to use them in the future, but not right now.

An archive can also exist on a website or blog. This would contain previous content from the past and may be organised in categories or date sequence to ensure easy navigation.

Typical Uses for Archives:

• Most files available on the Internet and on electronic services like America Online are distributed as archives. Two benefits of using archives for electronic file distribution are that only one file transfer operation (“download”) is required to obtain all related files and file transfer time is minimized because the files in an archive are compressed.
• It is often useful to send a group of related files to an associate. Rather than distributing individual files it is often easier to distribute the files as an archive to benefit from the file grouping and compression.
• Some files are important but not used often. To save disk space simply compress these files into an archive when they are not used and decompress them only when needed.

Archive formats:

• Zip files are the most common archive format. Zip files can span multiple disks and provide both compression and file grouping. Zip files created by WinZip can have a .zip or .zipx file extension.
• TAR, Z, GZ, TAZ, and TGZ files are often found on Unix-based Internet sites. TAR stands for “Tape ARchive”. The TAR format does not provide compression; it is used only to group files. GZ and Z files are gzip files. GZ and Z files cannot contain multiple files. TAZ and TGZ files are TAR files compressed in the gzip format. Since almost all new archives are created in Zip format, WinZip does not provide facilities to add to or create files in these formats (however, all other WinZip functions are supported).
• File formats such as UUencoded, XXencoded, BinHex, and MIME are used primarily to transfer binary files by Internet e-mail. If you encounter one of these files, you can open it and extract its contents with WinZip. You can UUencode an archive using the UUencode entry in the WinZip Actions pull-down menu.
• WinZip also handles most files in the old Microsoft Compress format (also known as LZEXPAND format). However, there are several variations on this format, and Microsoft has not released documentation on these variations. WinZip issues an appropriate message if you attempt to decompress a file not supported by your version of Windows. Microsoft Compress files usually end with a trailing underscore, for example, “commdlg.dl_”. Like Z and GZ files, Microsoft Compress format files contain only one file. This format is used for many files on the Windows 3.1 distribution disks and many older Microsoft products. Note that not all files ending with an underscore are Microsoft Compress format files.
• The Microsoft CAB (short for Cabinet) format is used by most Microsoft setup programs, including those used to install Windows. CAB files provide both file compression and file grouping. You can use WinZip to open and extract the contents of CAB files. WinZip will handle most self-extracting CAB files.
• LZH and LHA are older file formats that provide both grouping and compression, like Zip files.
• Files with the .BZ2 extension represent individual files that have been compressed using the bzip2 program typically found on UNIX or Linux systems. Bzip2 is a data compressor and not an archiver. Therefore, .BZ2 files do not contain multiple files. WinZip does not provide facilities to create .BZ2 files, but you can use WinZip to open and extract the contents of .BZ2 files.
• RAR is a compression and archiving format. The compression technology is proprietary however the decompression technology is not. WinZip does not create .rar files, but WinZip can view and extract the contents of .rar files. To create Rar files you need to use a program like Winrar.
• 7Z is a compression and archiving format. The compression technology is proprietary; however, the decompression technology is publicly available under the GNU Lesser General Public License. WinZip does not create .7z files, but WinZip can view and extract the contents of .7z files.
• IMG is an archive format used for creating images of disks. The images can then be stored and used to restore the disks. WinZip does not create .img files, but it can view and extract the contents of .img files.
• ISO is an archive format that is used to make images of optical disks. These images can be stored and used to replicate the disks. WinZip does not create .iso files, but it can view and extract the contents of .iso files.

Source: Winzip.com