Although the iPhone has a lot less variation than, for example, Android handsets, there are still several editions with a major disparity in prices. Here's our guide to what you get with each handset, which may help decide whether it's right for you.
iPhone 3G or earlier
This model is now difficult if not impossible to buy new, but you may be able to pick it up cheaply on the second-hand market, making sure of course you buy from a reliable source prepared to guarantee it is in good working order. It's fairly basic by today's standards, lacking a video camera. It can connect to the App Store, but isn't compatible with all apps, and doesn't receive software updates from Apple.
iPhone 3GS
This is the oldest currently supported Apple handset. You'll generally only get it on a pay as you go basis: it's £319 from Apple without contract, though you can get it for £20 cheaper direct from some networks. It's a faster than the 3G (hence the "S" for "speed") and adds a video camera and voice control. It runs iOS4, the first version of Apple's mobile operating system to support multitasking.
iPhone 4
This costs between £400 and £500 in unlocked/no contract form (or more if you get a higher capacity 32GB version.) For two-year contract deals you'll have to pay around £35 to £40 a month to get the handset free. The biggest difference is inside the phone, where you get a new processor and twice the memory, meaning faster and smoother performance. There's also a so-called "retina" display, which Apple bills as meaning that from 12 inches away, the screen as detailed as the human eye can detect. There's also an extra camera on the front, which can be used for video chats. These are free to other Apple devices over Wi-Fi.
iPhone 4S
This is the latest model, costing just under £500 to buy outright, while the cheapest two-year contract with no upfront cost is just over £40 a month. While it has sold well, it didn't bring as many changes as some had expected (which may be why it wasn't branded as the iPhone 5.)
It brings a longer battery life and a dual-core processor, which means it's more likely you be able to use the phone even while it's running demanding processes such as video editing in the background, while games should run much more smoothly. It's also the first iPhone available in 64GB version, albeit at a much higher price. Note that some of the new software features that debuted with this iPhone 4S, such as voice control "assistant" Siri and a iPhone-to-iPhone text messaging system are available on the iPhone 3GS and iPhone 4 with a software update.
