What is a tar.gz File, and How Do I Open It?

A tar file, often called a tarball, is a collection of files wrapped up in one single file for easy storage. Rather than keep track of a whole folder of files, you only need to keep track of one. Tar files are often compressed after being created, giving it the .tar.gz file extension. Technically these are TGZ files, but nearly everyone calls both .tar and .tar.gz files simple “tar files.”
by Anthony Heddings via How-To Geek