.bz2 File — Bzip2 Compressed File

BZ2 files use bzip2 compression, an open-source algorithm created by Julian Seward in 1996 that achieves better compression ratios than gzip at the cost of slower speed. Bzip2 uses the Burrows-Wheeler Transform followed by Move-to-Front coding and Huffman coding to compress data. Typical bzip2 output is 10-15% smaller than gzip for the same input, making it popular for distributing source code archives where download size matters more than compression speed. Like gzip, bzip2 compresses single files and is commonly combined with tar to create .tar.bz2 (or .tbz2) archives. Bzip2 compression is significantly slower than gzip but decompression speed is comparable. The algorithm uses block-based compression with configurable block sizes from 100 KB to 900 KB, where larger blocks generally produce better compression. Bzip2 was widely used for Linux source code distribution (particularly kernel sources and GNU packages) before xz superseded it for many projects. The format includes CRC-32 checksums for each compressed block, allowing partial recovery from corrupted archives. Bzip2 remains supported by all Unix-like systems and most archiving tools.