Final answer:
A write blocker is a device used in digital forensics to ensure data integrity by preventing modifications to the original drive during investigation.
Step-by-step explanation:
A write blocker is a device used to prevent forensic software from modifying a drive while accessing it. Write blockers are crucial in the field of digital forensics because they allow investigators to access and copy data from a storage device without altering the original data, which is essential for maintaining the integrity of the evidence. These tools can be hardware-based or software-based, with the former being physically inserted between a computer and a storage device, and the latter being a software application that blocks write commands at the operating system level.