Define three types of user mode to kernel mode transfers?

 The three types of user mode to the kernel mode transferred occurred due to the:

It is mainly occurred due to the interrupt when, it send to the central processing unit (CPU).It also occurs due to the hardware exception and when the memory is access illegally as it is divided by the zero. It is mainly implemented or executed by the trap instruction as the system are basically executed by the program.

What's the rest of it? lol