From 7-Zip Software:

The main features of 7-Zip: High compression ratio in new 7z format with LZMA compression. Supported formats: Packing / unpacking: 7z, ZIP, GZIP, BZIP2 and TAR; Unpacking only: RAR, CAB, ISO, ARJ, LZH, CHM, MSI, WIM, Z, CPIO, RPM, DEB and NSIS. For ZIP and GZIP formats 7-Zip provides compression ratio that is 2-10 % better than ratio provided by PKZip and WinZip. Self-extracting capability for 7z format. Integration with Windows Shell. Powerful File Manager. Powerful command line version. Version 4.57 supports WinZip-compatible AES-256 encryption for .ZIP archives and 7-Zip can unpack MSI and WIM archives now. Also there are some speed optimizations.