Do you apply sunscreen even indoors? Please recommend an effective sunscreen.

I've been applying it diligently because I heard that UV protection is important, but

Whenever I go out, I always apply a generous amount the size of a coin before leaving.

I'm wondering if I should apply it when I'm at home or indoors.

Will there be a significant difference in irritability indoors depending on whether or not I apply sunscreen?

What are some effective sunscreens?