bada wrote:"jailbreaking" a phone means you "unlock it" so that it can work with any cell phone carrier.
When you get your phone from a provider, it is locked to only work with that provider.
So with your iPhone, you have AT&T. But you could jailbreak it so you could sign up with Verison, T-Mobile, etc.
It also allows your to load 3rd party apps instead of just the ones on iTunes.
Pretty sure that is what jailbreaking means... or maybe jailbreaking is just for the apps and "unlocking" is for the providers.
sure First Off could give a better explanation
here's a good car analogy I came up with:
Unlocking - being able to change the brand
of gasoline (your wireless provider). Not enough shell gasoline stations in your area (bad cell reception?)? you can switch to Chevron. The big plus is if I take my car to another country I can just use their gas (say a french wireless provider), rather than renting a car. it's cheaper to buy gas then to rent, get it?
Jailbreaking - being able to swap parts
of your stock engine (the phones software) for after-market parts. just like it would void your car warranty, once you do this to your phone you are on your own.
Rooting - being able to fully tune
the parts of your engine, to optimize performance. just like you can break your car engine by setting the rev limiter to 10,000 RPM, you can cook your phone by tunning it to work much faster than it was intended.
in more detail (i was bored today...
Unlocked - I bought the phone (used and) unlocked, which means that you can change the carrier. you can change between similar careers - so that means AT&T and T-Mobile can switch (SIM Card based), and Verizon and Sprint can switch (non-sim card). You have to get a code from your wireless provider or pay for an unlock code (someone else has acquired but hasn't used) via ebay. you kinda have to trick the provider into thinking you are an international business man if you want to get the code.
Jailbreaking - essentially means you can install custom applications that hackers make. example: you can install a "wireless tethering" application into your phone. why is this useful? if you have a laptop and you are on the beach, you can get wireless internet via your cell phone's get-it-anywhere internet capabilities.
Rooting - basically puts you in total control. let's you do things like overclocking or diverting the power reserved only for 3D games to be used to make common tasks of the phone much faster.
these three things can all be done independent of each other, but they really work well when combined.