What happens when you take a photo at the right angle?
Some programs such as Firefox come in .tar.gz packages but don’t have to be compiled. You can just extract the file anywhere and start using the program immediately. You can check whether a program will have to be compiled or not by searching for the following files: configure, autogen.sh, Makefile and Jamfile. If you don’t find any of these files, it probably doesn’t need to be compiled. Just search for the program executable (in the case of Firefox: ‘firefox’) to run the program.