On the other hand, Apple made it impossible for iPhone users to install a single application (as of yet). But of course thanks to hackers there is always a way around this issue. But it won’t be easy. And it will be risky. Some users even ended up with a dead iPhone. That’s why all the tutorials online on this matter mention the following before the guide begins: "Do this at your own risk."
The workaround is called ‘jail breaking’ your iPhone. A simple Google search will give you the information you need. But be aware that each firmware might have a different jail break process. So make sure to check what firmware your iPhone is running prior to attempting anything.
After the jail break, you will be able to add an application called ‘Installer’ to your iPhone where it will give you access to hundreds of iPhone applications. But you will be facing another problem. The iPhone’s memory is split into two partitions. One holds 300Mb (used for system files) and the rest is for your media files (iTunes music, photos, etc).
In order not to run into problems, you need to configure your iPhone in a way that it installs the applications on the second partition. Again, a simple Google search on this matter will help.
I told you it won’t be easy. Luckily, you can get an unlocked and jail broken iPhone off ebay to save yourself a lot of pain and agony.