Flash to Another Carrier

• If you plan on switching carriers but absolutely love your phone and can't find anything close to it, you may consider flashing your phone. This is essentially the same as unlocking a SIM card slot to be used with different carriers. Examples are Verizon Wireless phones being flashed to Cricket or MetroPCS. Being flashed to another carrier is the only category that a non-smartphone can be in. Smartphones can be flashed in this manner.
  
  

Flash a ROM

• When an Android phone is rooted, you gain full control of the phone. You are able to install apps that won't work on non-rooted phones as well as change the entire setup and feel of the phone. The most common way to do this is to flash a new ROM onto the phone. The ROM contains the look, feel, functionality and even some apps for the phone while still giving the user choices and control.
  
  

Flash a Kernel

• Power users may go further than flashing just a ROM and flash a new kernel onto the phone as well. A kernel controls deeper functions of the phone and allows users to demand more power. Users who overclock their phones flash kernels over the existing one.
  
  

Adobe Flash Player

• Many modern smartphones are capable of running Adobe Flash Player. This allows the phone to browse websites' built-in Flash almost as well as a computer depending on processor power as well as screen size. While this is used to describe "flashed phones," it is the least common use of the term.