About Zip Files and Other Archives

What is an Archive?

Zip files are the most common archive type of file. Archives are files that contain other files. Typically the files in an archive are compressed. Archives have various extensions (name endings), such as ZIP, ZIPX, LZH, LHA, GZ, or CAB, depending on how they were created. Archives make it easier to group files and make downloading and copying these files faster.

Typical Uses for Archives:

• Many files available for downloading from the Internet are distributed as archives. Two benefits of using archives for electronic file distribution are that only one download operation is required to obtain all related files and download 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.
  
  

What is a Self-Extracting Zip File?

A self-extracting Zip file is an executable program file (.EXE file) that includes both a Zip file and software to unzip or "extract" the contents of the Zip file. Users can unzip the contents of a self-extracting Zip file by simply running it. This is convenient because the end user does not need an unzip program (like WinZip^®) to unzip files from these self-extracting archives.

WinZip Self-Extractor Personal Edition, included with WinZip, creates Windows self-extracting Zip files.

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 email. You are not likely to encounter one of these files. If you do, you can open it and extract its contents with WinZip. You can UUencode an archive using the UUencoded File button on the Tools tab of the ribbon.
• 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.
• 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.
• VHD and VMDK are archive formats that represent Virtual Hard Disks or Virtual Machine Disks.  WinZip does not create .vhd or .vmdk files but it can view and extract the contents of these files.
• XZ files are compressed using the LZMA2 compression format. 7z file often use this compression format.