If you've never seen Steve Jobs introduce the first iPhone, please do. Even if you do not care about "ancient" history its a fantastic example of top notch presentation skills and communication of new ideas. Immense complexity, simplified.
The first iPhone didn't have apps. The web was it as far as extending its primary functionality. But then the computer science and programming geeks got a hold of the iPhone and started tinkering.
A few days after the original iPhone became available in July 2007, developers released the first jailbreaking tool for it, and soon a jailbreak-only game app became available. In October 2007, JailbreakMe 1.0 (also called "AppSnapp") allowed people to jailbreak iPhone OS 1.1.1 on both the iPhone and iPod touch, and it included Installer.app as a way to get software for the jailbroken device. From Wikipedia.As you can see from day one, the potential to run programs (now known as Apps) was baked into the iPhone. It wasn't just a phone, it was a miniaturized computer with a direct connection to the internet.
For an indepth look at the reasons and history for Jailbreaking, I point you to Wikipedia: http://en.wikipedia.org/wiki/IOS_jailbreaking
So you made it this far (or skipped) in this blog post. What does Jailbreaking mean to you! It means several things in terms of installing apps from an alternate app store called Cydia. After you jailbreak, the Cydia app becomes the primary method of finding, trying, buying (some paid and some free) apps. This includes things from quick-access to settings via my favorite tweak SBSettings to complete icon and background theme system called Winterboard.
|Home Screen of the Cydia "App Store"|
|SBSettings quick access toggles|
It also lets developers release software that Apple would prefer not to include in their app store. The best example of this is My3G. This paid app allows you to bypass certain download limit restrictions when you are on 3G. It also allows FaceTime over 3G (your mileage depends on data speeds) and downloading larger apps and podcasts over 3G (the normal limit is 20MB then you need to be on wifi). Another great paid app is MyWi. This turns your phone into a mobile hotspot without having to pay your Cell Phone provider an additional fee (on top of your already expensive data plans). One word of caution, this is not for heavy use. I only connect my Wifi iPad 2 to it when I need some internet.
|My3G app that removes download limits for green checked apps.|
For folks on iPhone 4S and iPad 2 (collectively referred to as the A5 devices as their CPU is the Apple A5 chip) need to use the ChronicDev Teams Absinthe tool. As of this writing their websites are seeing heavy traffic however you can follow this guide with links to the software to download: http://iclarified.com/entry/index.php?enid=19462&laid=
Please feel free to comment and I'll look to update this post and respond in the comments as possible!