Skin is the largest organ in the body covering the body and protecting it from injury, regulating temperature and preventing from becoming dehydrated. Skin has two main layers of cells called the epidermis and the dermis. Epidermis is the  outer layer of the skin and contains three main kinds of cells:
- Squamous cells - flat cells that are packed tightly to make up the top layer
- Basal cells - tall cells that make up the lower layer
- Melanocytes - cells that produce a dark pigment (melanin), the substance that gives skin its colour
Basal cells multiply and the older cells move upwards in the epidermis. When they flatten out and form a layer they become squamous cells. When skin is exposed to the sun, melanocytes make extra melanin to protect the skin from getting burnt. This is what causes skin to tan. Melanocytes are also in non-cancerous (benign) spots on the skin called moles or naevi. Most moles are brown, tan or pink in colour and round in shape.

Dermis is the layer under the epidermis. It contains the roots of hairs, sweat glands,  blood and lymph vessels and nerves.

In the following sessions, you will find more details about different types of skin cancer and pre cancer lesions  as well as process of skin check at QLD skin cancer clinic and self check tools  to monitor your skin for skin cancers.