A .tar.7z file is a created by first bundling multiple files into a single .tar (Tape Archive) file and then compressing that file using the 7-Zip ( .7z ) algorithm. This double-process is similar to the more common .tar.gz , but it uses the 7-Zip LZMA/LZMA2 method for potentially higher compression ratios. Why Use .tar.7z ?

: The 7-Zip algorithm (LZMA) generally achieves a much higher compression ratio than standard ZIP or GZIP, making it ideal for large-scale archival.

: Since 7-Zip treats the entire .tar file as a single data stream, it can find redundancies across multiple files, further reducing the final size. How to Create and Extract

Users typically combine these two formats to solve specific limitations of each: