HTC One X (white) - 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.

Front-facing cameras are great for video calling (if your phone has the functionality), or seeing what you and your friends look like before you take a picture.

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

The quality of the videos you record on your phone depends on the resolution and frames per second. VGA is lower than 720p (HD) and 1080p (full HD).

Listen to your favourite tracks on the go. You could even download tracks or transfer them from your PC or Mac.

Transfer music and pictures from your PC or Mac straight to your phone.

Make video calls through your phone's front-facing camera.

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.