1):- To spot the differences between normal skin moles and would be malignant skin growth we must follow the ABCD rules, which means—

A— Asymmetry: If the skin mole is not even on both sides, it needs particular test to diagnose melanoma.

B— Border: If the skin moles are surrounded by an irregular and blurred border.

C—Colour: Skin mole colour plays an essential role to define the nature of mole---benign or malignant. If the colours of skin moles appear to be uneven and show many shades of black, brown, red or purple, it is something different from the normal skin mole. Such moles needed further investigation. ( maybe skin cancer)
Read more: Cancerous moles