Sunscreen, also known as sunblock or sun cream, is a photoprotective topical product for the skin that helps protect against sunburn and most importantly prevent skin cancer. Sunscreens come as lotions, sprays, gels, foams (such as an expanded foam lotion or whipped lotion), sticks, powders and other topical products. Sunscreens are common supplements to clothing, particularly sunglasses, sunhats and special sun protective clothing, and other forms of photoprotection (such as umbrellas).
Read more on wikipedia