1. What is BDM, and what is its use?

Background Debug Mode (BDM) interface is an electronic
interface that allows debugging of embedded systems.
Specifically, it provides in-circuit debugging
functionality in microcontrollers. It requires a single wire
and specialized electronics in the system being debugged. It
appears in many Freescale Semiconductor products.

3. What is high debugging?

it is helped to recure the bugs. a program has problem that
time this debugging is helped to solve the bugs is easily,
this is the method of the recure bugs in the programming