Named after its Russian creator, the RAR format, standing for Roshal Archive, is a compressed file type. The compression technique used to create RAR files is proprietary and has been licensed to other paid and freeware compression file applications. The RAR format also provides features such as repair, which will attempt to restore part or all of the file when physical damage has occurred. The RAR format established itself as a rival to the ZIP file format due to its superior compression ratios.
The RAR format allows for an extremely large potential file size, with 20 Exabyte's being the upper limit. The format permits spanning across multiple RAR files. This sometimes leads to the file extension being renamed from .RAR to .R01,.R02 etc. This is particularly useful when an archive needs to be transferred to removable media such as a memory card or CD/DVD. RAR, along with several other lossless file compression formats, is based on Huffman encoding.
The .zip file extension is the most well known file type related to compressed and archived files. First released in 1989, the format is still widely used and is built into Microsoft Windows releases since 1998. It is also supported by Apple's OSX operating system. The ZIP format supports compression via several different techniques and even supports simply archiving of files without compression. Despite being 20 years old, the ZIP format looks set to continue to thrive whilst bandwidth and storage remain relatively costly.
The compression techniques used to create a .zip file do so by compressing each file individually. This has the advantage of potentially using different appropriate compression techniques for each file within the archive, however under normal circumstances it limits the potential compression capability. Although the ZIP format allows for up to 10 different types of compression to be chosen, the DEFLATE method is the most common. DEFLATE is based on Huffman coding.