7z, ZIP, CAB, RAR, ARJ, LZH, CHM, GZIP, BZIP2, Z, TAR, CPIO, ISO Files
7z, ZIP, CAB, RAR, ARJ, LZH, CHM, GZIP, BZIP2, Z, TAR, CPIO, ISO, MSI, WIM, NSIS, RPM and DEB formats (格式)
This is all compression format. After compression, the file will became smaller for upload/download/storing. the theory behind it is quite simple, but it is not easy to make it very high compression rate.
Compression...
Before compression. Data = 1111111111 (10 Bytes)
After compression. Data = 10.1 (4 Bytes) <-- For easy understanding.
Recommended Compressor:
7zip - It can unpack all the the formats listed above. Small in size. Free!
WinRAR - For RAR decompression.
Note:
7z can't extract some RAR file.
Recommended Media compression type:
Multimedia files - RAR (Highest Compression)
Other - 7z (Highest Compression)
Official Website: http://www.7-zip.org/
Download Link: http://downloads.sourceforge.net/sevenzip/7z465.exe
For me rar files are very important. Once I lost all of them and was really disappeared. I used a search engine, I was lucky and found an one tool, which relieved me and probably can help in other situations, for example in this too - rar fixer.