The tar file type is used to combine multiple files into a single archive. Tar actually means "tape archive," because tar's original purpose was to be used on tape backups - that should tell you how old this format is. Linux systems still use the tar format, and it continues to enjoy widespread use to this day.
Tar files, with the extension .tar, are often called "tarballs."
This is a companion discussion topic for the original entry at https://linuxconfig.org/how-to-extract-tar-file-on-linux