Remember, more than actually being difficult, Linux has been taught to be so. We would like to adhere to a new statement saying, Linux is different and not necessarily difficult.
Generally, a source code comes as a bundle which is a compressed file having an extension -- <strong>.tar, .tar.gz, .tgz, .tar.bz</strong> <em>et al</em>. They are often known as <strong>tar balls</strong>.