With beach season in full swing, the reminders to wear your sunscreen when you head outside are ever-constant, and for good reason.

Not only does sunscreen reduce the likelihood of developing skin cancer, by offering a degree of protection against the UV radiation pumped out by the sun, but it even prevents us from getting a nasty sunburn.

While we’re often and accurately told about the benefits of sunscreen, we’re not as filled in on why exactly our skin reacts the way it does in the presence of a beaming sun or tanning bed.

But thanks to this Youtube segment by the popular SciShow, we no longer have to be in the dark about sunburns and tans.

As it turns out, it’s all about self-sacrifice. Because UV radiation can trigger our cells’ DNA to mutate, possibly out of control — as with cancer — the body has developed a series of preemptive defense mechanisms to protect itself.

It’s these defensive maneuvers that are really causing our skin to tan or burn, not the sun or UV radiation itself. Much like how a fever is our body’s attempt to drive away foreign invaders rather than being directly caused by the latest common cold virus.

So put on the sunscreen, watch the video, and learn some more interesting factoids about why and how sunburns and tans happen.