In general, optic disc cupping can be 'physiological' or 'pathological'.
Physiological means there is no disease that causes it, i.e. it is normal for that particular person.
Pathological cupping means there is a disease that causes the cupping, i.e. glaucoma. Optic discs can also appear cupped if there is an optic disc pit or an optic disc coloboma.
The distinction between physiological and pathological can sometimes be difficult to make. Sometimes, it may require multiple visits over a period of time with sequential tests like OCT scans of the retinal nerve fibre layer and visual field tests. These tests help to determine whether the condition is pathological or not.
Usually, diseases like glaucoma would cause a deterioration in the scan results or visual fields over a period of time. Meanwhile, with other conditions, there may be no changes at all.
Do consult with an eye doctor if there is any concern at all that your optic disc is cupped.