Software

Software is becoming a very specialized profession. It is getting to the point, and probably already there, where it is really not possible to know enough about every type of skill.

Web software, application software, mobile software, directory submission software, and many more. There are so many specialties that it is at the point where you really have to pick something and specialize in it.

That is easier said than done as well because you don't want to pick incorrectly. Just ask anyone who picked mainframe programming how they feel about their choice right now.