Apple iPhone 3GS 8GB - Specifications

The operating system you use (like iOS, Android™ and Windows Phone) will depend on your phone.

The size of your phone's internal memory will determine how many pictures, videos and music tracks you can store on your phone. Some phones also come with a memory card slot so you can increase the memory.

Mobile phones are built with different screen technologies. Generally, the higher the pixels per inch (ppi) number, the clearer the screen will be.

You can make calls, send texts and browse the internet on a 2G network. If you're looking for faster web browsing, you might want to look at 3G-enabled phones.

This is where in the world your phone can be used. Some phones can be used worldwide, while others are restricted to the UK or Europe.

If your phone's Wi-Fi enabled, you can connect wirelessly to the internet when you're in a Wi-Fi hotspot (including airports, restaurants and train stations).

GPS allows you to pin-point your location using satellites. So you can use SatNav applications on your phone, or even find somewhere to eat when you're out and about.

Generally, the more megapixels your phone's camera has, the sharper the image will be.

With auto-focus, you can click or tap to take a photo and your phone's camera will automatically focus on the subject.

The operating system of your phone will come with its own application store - where you can download apps and games to your phone (some of them for free).

Make a phone call without having to search through your phonebook. Voice-activated dialling means you can simply say the name of the person you want to call and the phone will dial their number automatically (you'll need to set this up first).

There are different types of email you can get on your phone. You can keep up-to-date with accounts like Gmail, Hotmail and Yahoo! - and with push email, you'll get your messages straight away.

Content Control stops customers under the age of 18 from accessing inappropriate content. This can be removed.