system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How does touching the glass of a headlight bulb make it burn out faster?
gpt
You leave oils behind on the surface of the bulb, which causes the surface of the bulb to heat unevenly as those oils/contaminants are heated up. 

Certain bulb types, like halogens, output enormous amounts of heat while they're operating. At these high temperatures, that uneven heating can compromise the structure of the bulb and eventually destroy it.