This function returns a compressed version of the input data using the DEFLATE data format, or FALSE if an error is encountered. The optional parameter level can be given as 0 for no compression up to 9 for maximum compression. If level is not given the default compression level will be the default compression level of the zlib library.
For details on the DEFLATE compression algorithm see the document "DEFLATE Compressed Data Format Specification version 1.3" (RFC 1951).
See also gzinflate(), gzcompress(), gzuncompress(), gzencode().