DFU

Recovery Mode is what your iPhone goes into when you are doing a standard iOS upgrade or restore, but you may want to put your iPhone into recovery mode for other reasons (often related to a jailbreak).
Remember, Recovery Mode is different than DFU mode because DFU mode bypasses the bootloader which allows for things like downgrading firmware. You can not downgrade firmware with Recovery Mode, you can only upgrade or restore.

Enter iPhone Recover Mode

Here’s how to enter into recovery mode, this works on the iPhone, iPad, and iPod touch:

1. Disconnect the USB cable from your iPhone, but leave the other side connected to your Mac or PC
2. Launch iTunes
3. Press and hold down the Home and Sleep/Power button on the top of the iPhone to turn off the iPhone
4. Press and continue to hold the Home button while you reconnect the USB cable to your iPhone, this will cause the iPhone to turn on
5. Continue to hold the Home button until an alert message in iTunes informing you that an iPhone in recovery mode has been detected, like the screenshot below:

Your iPhone is now in recovery mode. If you have not launched iTunes, you will see the familiar screen of the USB cable pointing at the iTunes logo signaling to connect the iPhone to iTunes to start recovery.
Once you’re in recovery mode, you can either restore the iPhone or adjust the firmware as necessary (you can download iPhone firmware here).
After restoring or upgrading firmware, your iPhone will automatically reboot and exit recovery mode on it’s own.

Exit iPhone Recovery Mode

You can typically exit recovery by doing the following:

• Hold down the home and power button for about 15 seconds, this shuts off the iPhone
• Press the power button to boot the iPhone

If you are stuck in recovery mode (or DFU) and you do not want to do a restore or firmware upgrade, you can use a tool like TinyUmbrella or RecBoot to escape too. If you are still stuck that usually means you must re-install iOS firmware.