The iPhone 4 is no doubt probably the most popular smartphone out there. And because of it's mobile capabilities, you're probably going to spend a lot of time on their 3G network or public wifi, rather than on your home internet (private connection). You should know that using public internet connection, much like using public restrooms, can be dangerous is the wrong parts of town. Your IP address makes you exposed to things like eavesdropping and deep packet searching, or just plain old hacking. And iPhone 4 VPN prevents this.

A VPN is a tool that can encrypt and tunnel your online data. These sound pretty fancy, but chances are that you really know what these are. Think of encryption as scrambling all your data, and creating an 'unscrambling' code that only you and the VPN have keys to. If another person sees what you sent, they have no idea what it means - they can't interpret it because it's in a language they don't understand. Only with the proper key can they decode your data.

Tunneling is just that. A virtual tunnel is created between you and the private network (VPN). This makes the sending and receiving of your data completely invisible.

You are then assigned a virtual IP address by the VPN. Rather than use your real IP address, the one that reflects your currently location and network identity, you use an IP from the VPN. Other websites, network admins, or unscrupulous third parties don't see you on your real network, they see you on the virtual network, to which they have no access to.

So it's easy to see how an iPhone 4 VPN can be useful for the protection of your private data.

How to get one

There is actually no hardware needed. For an iOS system, there are basically two type of VPNs, and both are able to be downloaded directly from the internet. They are called PPTP and L2TP.

PPTP is an older, lighter version of the VPN, so many users prefer it for its speed. This is best for unblock sites, bypassing firewall restrictions, and other types of activity that require an IP change.

For those looking for security and anonymity, the L2TP VPN is preferred. L2TP uses much better data encryption, called IPSec. This may involve a more complicated setup process, and will require more bandwidth, but if you're concerned about privacy or security, L2TP is the way to go.

An iPhone 4 VPN service will require a monthly fee, costing anywhere from $3 per month up to $20, depending on the brand of service, the level of encryption, and the length of your subscription. Obviously not all services have the same features, and things like which servers you get access to or the amount of bandwidth you're allotted may be limited for cheaper accounts. Still, unlimited bandwidth VPN packages are common, and some VPN services offer access to hundreds of servers across the world.