.rar

File or group of files compressed with RAR compression; uses a higher compression ratio than typical ZIP compression; incorporates a proprietary compression algorithm now used by other compressors such as 7-Zip (for 7z files).

The RAR compressor can also create spanned archives, or compressed archives that are split across several files; these files may have file extensions from ".R00" to ".R99" or may all have the standard ".RAR" extension.

The name "RAR" comes from "Roshal ARchive" since the RAR compression algorithm was developed by Eugene Roshal.