system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 What are skin tags and why do we get them?
gpt
A skin tag is actually a benign tumor that usually forms where skin creases, like the neck or armpit, and sometimes the eyelids. They are almost always harmless. They're very common (moreso in women than men), and thought to be formed by skin rubbing on skin, but the exact cause is unknown. 

They're safe to leave and safe to have removed - they don't grow back. Be sure to consult a dermatologist for advice.