zlib: zlib (compression library) zlib: zlib: zlib is a general purpose thread safe data compression library. The zlib: data format used by the zlib library is described by RFCs 1950 to zlib: 1952 in the files ftp://ds.internic.net/rfc/rfc1950.txt (zlib format) zlib: rfc1951.txt (deflate format) and rfc1952.txt (gzip format). zlib: zlib: zlib: zlib: zlib: