Multi tasking - apps open at same time

Third party apps don't stay open on the iphone. Apple doesn't allow that. So that's how you can be sure

 

iPod,Safari,Mail and Phone are the only one that can stay open on stock firmware (not jailbroken). Safari is the most memory intensive one of the 4 though.

 

To force-quit any app to ensure it doesn't stay running, hold the power button until the slider comes up and then hold the home button until you're put back on the home screen.

 

you can use backgrounder from cydia. it doesnt quit your apps, but hides it in the background. when you want to open it again, it remains the same as when you closede it.

 

Never heard of that. Sounds pointless.

To force-quit any app as standard just hold down the home button while you're in the app you want to quit. It will close itself after a few seconds and wont be running in the background.

Alternatively, if you're jailbroken there are a number of third party apps that can show you what's running in the background and quit them too.
Kirikae and MemInfo are 2 I know of and use on a regular basis. (Both available from Cydia)

 

The method using the home button alone is for older iPhones. Newer ones/newer OS upgrades will activate the Apple voice search instead of force-quitting. The method described is the new way to do what you had described.

 

What he wrote: