Applying sunscreen onto your skin does protect you from the harmful UV rays of the sun, however, you have to be aware that a lot of sunscreens in the market don’t do anything at all. The high SPF rating is not an indicative measurement of the efficacy of sunscreen. The SPF rating explains how long the sun screen should protect you from the effects of the sun, and of course, this amount of time varies depending on your type of skin, and where you are “sunning” yourself.
According to research, the active ingredients zinc oxide and titanium dioxide cover the entire ultraviolet spectrum (both UVA and UVB rays) and a concentration of at least 18% of one or the other is recommended for the best sun protection*.
A list of reliable sunscreen brands can be viewed here.
*Source: Ocean and beach-loving blog The Scuttlefish