What is XD bit ?

What is Execute Disable Bit (XD-Bit)?

Execute Disable Bit (XD-Bit) is a system feature that, if present and enabled, allows the notebook’s processor to distinguish between bits of code that should be executed and the ones that cannot be executed because they pose a threat to the system. When a malicious worm attempts to insert code into the buffer, the processor disables the code execution, preventing damage or worm propagation. In other words, even if infected code is present on the notebook, as long as the processor does not execute it, the code cannot cause any damage. This process of disabling the code execution is called Data Execution Protection or DEP.