system
Given the following post, respond as if you're commenting on Reddit:
human
Why doesn't water fall out of a sponge?

Is it just surface tension and molecular attraction between the water and the sponge itself?
gpt
Yes in essence it's due to molecular attraction but importantly it's also because you have such small capillaries within the sponge. At these small length scales surface tension effects are important.

The walls of the sponge's capillaries would rather be covered in water than air. With this, and the fact that the capillary walls are so close together, means the water is happily held in place.