Most of us understand acne as the irritating pimples that are commonly found on the forehead and the face.
However, there are different acne types and many of these present themselves in the form of serious and chronic skin conditions.
The simplest way of understanding different types is by dividing them into two basic categories:

Severe acne

Mild-to-moderate acne

Severe Acne It is characterised by two typical features:

It can't be cured by using OTC (over-the-counter) medications and requires expert medical advice for treatment

It is long-term in nature and some individuals have been known to experience severe forms throughout their lives

The most common types in severe acne include:

Nodules

Spots created due to nodular acne are much larger in circumference and are quite painful.
The nodules are like thick, hard bumps on the surface of the skin and they usually cause scarring.
Without medical treatment, unsolved cases of nodules translate into impaction, i.
e.
presence of thick closely-packed, pit-shaped nodules for life.

Cysts

Cysts, or acne cysts, are sometimes misunderstood as nodules.
However, cysts are a different type of acne and are characterized by the presence of thick pus.
These can be very painful.
Make sure never to squeeze or prick them as this activity can cause permanent scarring.
Squeezing cystic acne leads to spreading the infection on a much larger scale.

Rosacea

Rosacea is typically found among people in the age group of 30+.
These are actually a complicated version of untreated acne vulgaris.
Rosacea begins as a slightly red lesion along the cheeks, chin and nose.
It is one of the most severe types and can even distort the nose, a condition that's known as rhinophyma.
Mild-To-Moderate Types Mild cases of are characterised by the following features:

These pimples are temporary in nature and even if left untreated, tend to resolve with time.

A few precautions like good hygiene and use of commonly-available OTC medications are sufficient to treat them.

The most common types in mild/moderate acne include:

Whiteheads - these are also called as closed comedones and are formed due to a complete blockage of the skin pore.
These are embedded deep within the skin.
In the absence of air, these lesions develop a distinctive white spot-like appearance.

Blackheads - these are called as open comedones as they have some level of exposure to the external air.
Here, the pores are only partially clogged-up.
Their defining black color is caused due to the oxidation of the melanin pigment that is found in the skin.

Papules - these are among the most common acne types and are easily recognizable due to their red, inflamed appearance.
Unlike the comedones (whiteheads or blackheads), papules have no visible 'head'.

Pustules (zits) - these are often confused with whiteheads, but pustules are actually the inflamed version of an earlier whitehead.
They have a typical red circle and the centre is usually yellow or white.