Did you know that the iPhone had a "Safe Mode?" Safe Mode on the iPhone has been apart of jailbreaking for years now, but many people still don't understand it. If your iPhone is jailbroken, Safe Mode will be invoked when MobileSubstrate (the Cydia support framework) crashes.
Desktop operating systems, like Windows and Mac OS X, have had a "Safe Mode" for a long time. On the desktop, safe mode is used for removing corrupted processes that may be causing the operating system to not function properly.
The iPhone has a "Safe Mode" for that exact same reason. A simple Cydia app called "Safe Mode Launcher" allows you to invoke the iPhone's Safe Mode with one tap. Let's take a look...