system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: why doesn't glue dry up in the bottle?

I've never understood why it doesn't dry up once you open the bottle...
gpt
This is similar to "Why doesn't water evaporate in the bottle?". The glue dries when the moisture in it evaporates into the air. Outside the bottle, there's a lot of air and not a lot of glue, so the moisture from the glue is evaporated easily. In the bottle, there is little to no air, so the moisture doesn't have anywhere to go but to stick in the glue. (The little air inside will reach its maximum moisture content before the glue dries)