Types of Minor Scales

Common types of Minor Scales
(demonstrated in A minor)

Natural Minor - no accidentals* (same as key signature).

Harmonic Minor - compared with natural minor, the seventh scale degree is raised by an accidental.

Melodic Minor - compared with natural minor, the sixth and seventh scale degrees are rasied by accidents only when ascending. When descending it reverts to natural minor.

Jazz Minor - compared with natural minor, the sixth and seventh scale degrees are raised by accidentals.
This is sometimes confusingly referred to as "melodic minor" in jazz contexts.
(You may want to think of it instead as a major scale with a lowered third scale degree.)