system
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human
ELI5:On an atomic/molecular level, Why does glue glue?

Why does glue glue and adhesive adhere on a micro scale.  
I understand the larger picture of surface area, surface texture and general bonding along with curing. But what is happening that allows the glue to bond at an atomic level.
gpt
There are a few theories, and it depends on the glue, but you already have a fair understanding of the basics: surface area.

Nothing is really smooth if you zoom in enough. There are valleys and ridges and bumps and holes. Now imagine 2 rough surfaces like that being placed together: nothing much will happen. But now fill in those gaps with something runny that will get into every crack and tiny space. When that stuff dries it isn't just a uniform shape like a zigzag that can easily lifted off another zigzag, the ridges and valleys are much more complex, and are in 3D and go in every direction, more like the branches on a tree. If you try to pull the glue out it won't come easily because some valleys or shafts might go left, some might go right, some forward, some back. Some might be straight, some might curve, but they are all filled with glue that would need to be pulled in every direction at once to come out of these spaces. Now that's only one object, the item you're sticking it to also has the same properties, so the glue is really getting into all these tiny spaces on 2 items, meaning they are then harder to come apart.

Another way glue can work is that atoms have positive and negative charges like magnets, and so like lots of tiny magnets they can actually kind of stick together.