The RAR File Extension Explained

Janis Elsts

Like the more popular ZIP archives, files with the .rar file extension are "archives" that contain one or more files or folders in a compressed form. These files are produced by file archiving software, the most common example being WinRar. Like most common archive formats, RAR employs lossless compression. This means that when you extract a file from the archive it will be exactly the same as it was before archiving. There also exist lossy file formats that discard some of the information in a file to compress it more efficiently. Most multimedia files (MP3, AVI and so on) that you're likely to encounter are already compressed using lossy compression, so compressing them with RAR won't produce a significantly smaller file.

Initially file archiving was used mainly to decrease the amount of disk space necessary to store a file. However, with large hard disks becoming more available and cheaper, compressed files are now rarely used for this purpose. Instead, .rar archives are now widely used when putting files online. There are several reasons for this :

* Compressed files lead to smaller download size and faster downloads. The RAR file format offers better compression than ZIP files, so the .rar archives are often smaller than .zip.

* One can put several files in one RAR archive, so the user only has to download a single .rar file.

* Multi-volume archives allow you to split a huge file (like a video) in smaller chunks that can be downloaded separately.

* Password protection - since anything you put online is typically accessible by anyone, the built-in password protection feature is needed to give a certain level of control over who can open the downloaded file.

Aside from downloadable files, the RAR file format is also used for backups, though this use isn't as widespread.

As I mentioned before, the most common software for handling .rar files is WinRar. WinRar is shareware, but there are numerous free RAR extractors available that can open RAR files. Note that since the .rar file format is proprietary, none of the freeware alternatives can actually create RAR archives. Nevertheless, I still recommend you get a RAR extractor, because you're going to encounter the .rar file extension sooner or later if you download files often.
About the Author
This article about the .rar file extension was brought to you by Janis Elsts, an experienced computer programmer. Janis has put together a list of free http://w-shadow.com/blog/2007/08/26/free-rar-extractor-list/'>RAR extractor software that you can use to open .rar files.
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