7zip is a compression/decompression utility program in Linux. You can compress single files, multiple files and folders recursively. If you have a 7z file which content is not known to you, you can view the files inside the 7z file easily:
If your .7z file is named myfile.7z, in Linux terminal, type:
$ 7za -l myfile.7z
l stands for list.
This outputs the included files in the 7z file. To decompress these files, check article: Extract .7z File in Linux