When we were kids, we were all told to put away our toys after we've finished playing with them. It takes time (and a lot of nagging) but eventually the message gets through. We still hear it when we double-click the home button on the iPhone and see all those recently used apps running in the background. We're not using them any more so we shut them down... and in the process, we get to feel good about the resources and battery power we're saving. It's like getting an instant reward for cleaning up your room.

So when Apple Insider ran an article arguing that force-closing iPhone apps doesn't make any difference at all to memory or resources, it struck a nerve. The habit, the article said, was "a waste of time." Other experts have even argued that re-starting apps from scratch takes up more resources and drains the battery faster.

We've been cleaning up for nothing.

I didn't like the sound of that so I asked my friend Andy Grignon what he thought. Andy was part of the original team that worked on the first iPhone, a product they were told at the time was an iPod that could make phone calls.

As you might expect, the truth behind the benefits of force-closing apps is a little more complex than it sounds.

"Technically they are correct," Andy said. "When you kill an app, all the resources associated with it are freed up. And when you want to use it again, you have to go through the usual start up process which does take a bit of time. But at the end of the day it's minimal at best."

The biggest drain on a mobile phone's battery, says Andy, is the screen, followed by the radios -- the Bluetooth and wifi that are constantly sending and receiving information. Compared to them, the effect of opening and closing apps is minimal, and for the most part leaving apps in the background is fine. "The operating system is fairly efficient at juggling multiple apps at the same time. It's such a non-event."

The only time leaving an app running in the background can cause problems is when the app is badly-written. Apps like Facebook and Twitter, for example, might conduct plenty of activity in the background but they're created by developers who know what they're doing and know how to minimize resource usage. But a poor app, created by a small shop, that's tracking your location and constantly making updates as new GPS co-ordinates come in could be costing you power.

"If an app has a bug that makes it do a whole lot of work every time your location changes, you're going to notice your battery changing a lot faster," says Andy.

That effect on the battery is the only way you'd know whether the app is written well or badly. So if you're noticing that your battery is emptying faster after you use certain apps from small companies, then clearing out your background apps won't do you any harm and it might just save your phone's juice.

"If it makes you feel good, then do it," says Andy. "I think it's kind of a hassle."