How to kill running application?

[susja]

Hello
I am just wondering how could I close application which I am not interested any more after I launched it. I understand that if I switch to another one it will run in background consuming some space. Not sure how it'll impact on device performance but I just think that less app using memory it should perform better.
Well hoe could I kill that running app?
Thanks

 

[MoonlitSonata]

Double tap the home button, hold down the app until it jiggles then click the red circle.

 

[susja]

Double tap the home button, hold down the app until it jiggles then click the red circle.

Great!
Thanks

 

[ggrreegg811]

Doing this frequently should help save your battery some as well!

 

[drb_52]

If you have gestures turned on, you can do a four finger swipe up to see the open apps. Do the four finger swipe down to close the bar.