IPhone problem! Helpppppp?

[Rachael]

Sometimes when I'm on my iPhone 4S it closes apps by itself, it happens on games, Facebook Instagram an other! It's so annoying does anyone else have this problem or know how to fix it?
Thanks in advance xx
ah thanks, is there anyway to stop this? or is it just a ongoing problem?

[Kayla]

Does the screen go black and then it boots you back to your home screen? That's not the iPhone closing apps, it's crashing. When an app gets too slow or is doing too many things at once, the app shuts itself down and resets.