Apple jailbrake Tethered defenition?

I'm still a little confused over tethered and untethered devises. What's the difference? I have an iPhone 4 and i can't jailbreak it unless its tethered and i don't understand what the limitations are. I know it has to be connected to a computer in order to be rebooted but what else?

Also, i have the phone with a company called H2O and i can't receive multimedia unless its jailbroken. Does tethered count?

Thats cool

To understand the difference, you must understand the definition of tether.

Tether: Tie with a rope or chain so as to restrict its movement

1.In the case of a tethered jailbreak, you'll have a fully jailbroken iPhone, but the jailbreak will be disabled every time you restart your phone (or if it shuts down from a dead battery). You will have to connect your iPhone to a computer and jailbreak it again. This essentially "ties (tethers)" your iPhone to a computer. Your phone will not be functional at all if it shuts down/restarts until you jailbreak it again.

2. An untethered jailbreak means you are no longer tied to a computer. Once jailbroken, it will remain jailbroken even if you restart/shutdown your phone. The only way to remove it is restoring your phone on iTunes.

3. There's also a semi-tethered iPhone. This means that like the tethered jailbreak, the jailbreak will disable once the phone has been restarted/shut down, but the phone will remain functional after you turn it back on. You will still be able to make calls, text, but won't be able to use Cydia content. That is, until you connect to a computer and jailbreak again.

4. With your H20 service, you need to set settings called APN settings. Normally, the iPhone doesn't give you access to these settings. If your iPhone is jailbroken, there's an App in Cydia called TetherMe that will allow you access to these settings, which you can then change and set to the H20 settings, which will enable MMS.

I hope this helps. Message me if you have any questions.

Edit:
In response to the spam you were given, all jailbreaks are ALWAYS FREE. You should only get them from the trusted jailbreak team. Right now, it's evasi0n. Any website that asks for something in return is a scam! This includes asking you for money, or asking you to do surveys or try products.