LZMA

LZMA (Lempel–Ziv–Markov chain algorithm) is a lossless data compression algorithm developed since 1998 by Igor Pavlov, the developer of 7-Zip. It has been used in the 7z format of the 7-Zip archiver since 2001. This algorithm uses a dictionary compression scheme somewhat similar to the LZ77 algorithm published by Abraham Lempel and Jacob Ziv in 1977 and features a high compression ratio (generally higher than bzip2) and a variable compression-dictionary size (up to 4 GB), while still maintaining decompression speed similar to other commonly used compression algorithms.

LZMA2 is a simple container format that allows multi-threaded compression and decompression using multiple separate LZMA streams. It is used in both in the 7z and the xz format.