Many of us have become used to buying things online for our families. Whether this is the weekly shopping, electronics or birthday presents we know what to expect when purchasing from a website.

A newer innovation is purchasing games and software for our handheld games consoles and mobile phones directly on the device -- the iPhone, iPad, 3DS or PSP for example. This lets you buy new games via a WiFi internet connection without even being connected to a computer.

The purchasing process on each device can be quite different -- in particular how you buy add-on packs from within these games. This is the ability to progress in a game by spending real money to buy in-game currency.

Most of these services require a password by default every time you make a purchase, but the iPhone and iPad doesn't. To make the purchasing smoother they don't require you to reenter your password for 15 minutes.

This doesn't sound like a problem until you come across free iPhone games like Pet Hotel or Smurf Villiage that you might download for your son or daughter and then hand to them to play. Within the first few minutes of these games you can make purchases for as much as £69.99, without a need for a password in the first 15 minutes.

There are a few things you can do to avoid this problem, which I'll discuss below, but I think the best advice is to play games with your children rather than let them play on their own. It means they will get more out of the experience, and you'll understand what they are getting excited about over breakfast.

Where your children are likely to play these games unsupervised, you can avoid the problem as follows:

Seperate iTunes Account

Create a seperate account on the device for your children that isn't linked to your creditcard:

1. Tap Settings, scroll down and select Store.
2. Tap Sign Out.
3. Tap Create New Account.
4. Follow the on-screen instructions.

If you need credit on this account use an iTunes giftcard or setup an iTunes allowance. You can then log into this account before your children use the iPhone.

Disable In-App Purchases For Everyone

Turn off in-app purchases for all users of the iPhone:

1. Tap Settings, then select General.
2. Scroll down and select Restrictions.
3. Tap Enable Restrictions and enter (and confirm) a passcode for the iPhone.
4. Tap the In-App Purchases slider so it switched to Off.

You have now disabled In-app purchases. Reverse this process to enable it should you require it in the future.

Log Out of iTunes After Purchasing

You can avoid the 15 minute password period by logging out of iTunes after making a purchase:

1. Tap Settings, scroll down and select Store.
2. Tap Sign Out.

You will now be prompted to login next time you make a purchase.