Dirty bit is used to show the

Answer: page that is modified after being loaded into cache memory

Explanation: The dirty bit is a flag associated with a page/frame that shows whether the page has been changed (written to) in memory since it was loaded or last saved to disk. It helps the operating system decide if the page needs to be written back to disk before being evicted.

• When the dirty bit is set: A write to the page has occurred, so the in-memory copy is newer than the on-disk copy.

• On eviction: If the dirty bit is set, the OS must write the page back to disk (write-back). If it is clear, the page can be discarded without writing.

• What the dirty bit is not: It does not indicate corruption, frequency of use, or that the page mapping is invalid. Those are tracked by other mechanisms (error checks, replacement metadata, and valid/invalid bits respectively).