Log
A log is a written record of what a program did and what went wrong, with the time of each event.
In a simple example
When a booking fails, the log says: 7:02 pm, could not save, missing phone number.
Why it matters to you
When something breaks, the log is the first place to look, and the first thing to paste to an AI helper.
Do not confuse with
A log records what already happened. It does not fix anything by itself.