SPF stands for sun protection factor and it is a measure of how well a sunscreen will protect your skin from the sun’s ultraviolet (UV) radiation. Specifically, it measures the amount of time it takes for UVB rays to redden skin when using the sunscreen as compared to how long it would take without using it.

It’s important to use sunscreen with at least SPF 30 to protect your skin from sun damage. It’s recommended to use a sunscreen with broad-spectrum protection, which means it protects against both UVA and UVB rays.

The amount of sunscreen you need to use will depend on the size of your body and the area of your skin that is exposed. The American Academy of Dermatology recommends using an ounce (around a shot glass full) of sunscreen to cover your entire body. This means if you are using a sunscreen with SPF 30, it would take 30 times longer for your skin to burn than if you were not wearing any sunscreen at all.

It’s important to note that sunscreen should be reapplied every two hours, or more often if you are sweating or swimming. Also, it’s essential to keep in mind that sunscreen should be just one part of your sun protection routine, it’s also important to seek shade, wear protective clothing, and avoid the sun during peak hours.