Acne vulgaris (or common acne) manifests as blackheads, whiteheads and pimples.
The blackheads are comedones and the mildest form of acne that looks like tiny black spots on the skin, usually around the nose. The black spots are a mix of sebum, bacteria and dead skin cells that have been exposed to air.
The whiteheads are also considered comedones like blackheads but are closed within the pore, thus they also block toxins from evacuating. They look like white raised bumps on the skin.
The pimples are red lesions that can be sensitive and painful to the touch. There are different names attributed depending on the size, the depth and severity of the pimple: papules, pustules, nodules and cysts. Pimples usually are filled with pus and popping them or squeezing them can lead to scarring.
However, non-popped pimples can also form scarring (new skin created that is different to the original skin). Scientists are still trying to understand the healing process of the skin, in particular, why new skin is created different to old skin.
But if you suspect something more than just acne vulgaris, such as possibly PCOS (polycystic ovary syndrome), itchy fungal acne, rosacea, etc, please consult a medical practitioner.