The "log queries not using indexes" option in mysql. What is it for?

Question

MySQL

I debug queries. I use the log-slow-queries parameter.
What does the accompanying parameter log-queries-not-using-indexes mean?
How can it be used? If you enable it, then even queries will be logged, the duration of which was less than the "long_query_time" parameter?
Please explain clearly. Thank you!

Answer 1

Log queries that don't use indexes...