Part one of a compressed archive split into several parts; usually created for saving a large archive on multiple disks. Some RAR files can be parts of multi-volume sequences. In WinRAR you can split a huge archive to a few smaller files, which are called volumes. They may have extensions .rar (the first volume), .r00, .r01, ..., or .part1.rar (the first volume), .part2.rar, ..., etc. If you need to unpack volumes, place all them to the same folder and start extraction from the first volume.