There are two types of sun screens - chemical and physical.
Physical blockers come in two forms - Zinc Oxide and Titanium. These work by creating a barrier on the surface of your skin and reflecting the harmful rays before they have a chance of penetrating. Physical blockers are the most effective but tend to sit heavier on the skin.
All other sun protections are considered chemical sunscreens. Chemical sunscreens sink into your skin and work by absorbing UVB rays and sending that energy safely out of your skin. These sunscreens typically feel more comfortable on our skin then physical sunscreens but most of them only protect against UVB rays. UVB rays are harmful and cause sunburns, but UVA rays cause wrinkles and sun damage. Most importantly, all three are responsible for causing skin cancer.
Recently an exciting chemical sunscreen has been approved after a rigorous FDA trial that absorbs and deflects both UVB and UVA rays. This ingredient is called mexoryl and is available over the counter!
Now that you know the difference between physical and chemical sunscreens I leave you with two important bits of knowledge. When searching for sunscreens you will be best suited by a broad spectrum lotion (meaning it protects against UVA and UVB). Also, sunscreen is typically only active for about 80 minutes so make sure you are reapplying regularly when outside!