Why cant I alt + tab when I'm in game? (any solutions?)

IGetHigh96

So when I'm ingame and I want to repeat a song or something I can't alt + tab, for windows 7 it used to work but now that I am running Windows 8 it doesn't let me alt+tab. Anyone know a solution in mind? Thanks:P

]Sake

This is a regular problem for Win8 users.
Hussein_2 made a guide just for this: How to Alt+Tab on Win 8.1