In computing, tar (derived from tape archive) is both a file format (in the form of a type of archive bitstream) and the name of a program used to handle such files. The format was created in the early days of Unix and standardized by POSIX.1-1988 and later POSIX.1-2001. Initially developed to write data to sequential I/O devices for tape backup purposes, tar is now commonly used to collect many files into one larger file for distribution or archiving, while preserving file system information such as user and group permissions, dates, and directory structures.
In computing, RAR is a proprietary file format, a lossless compression algorithm used for data compression and archiving, developed by the Russian software engineer Eugene Roshal. RAR uses a compression algorithm based on the LZSS which, in turn, is based on the LZ77, Thomas James Storer and Szymanski (1982). The dictionary size can vary between 64k and 4 Mb. The RAR is slower than ZIP, but has a higher compression ratio. RAR Another feature is that it has a better ZIP data redundancy. The format also allows what is known as a solid compression for compressing several files together, so that a single dictionary applies to all information, so that the compression is greater.