Static cling is part of it

Amino acids are arranged in a 3d matrix that creates a patch or a pocket with a particular pattern of positive and negative charges that complement a pattern of charges on the other molecule (the ligand). There's are also interactions involving hydrophobic vs hydrophilic molecular affinities, as well as overall physical shape.

When binding occurs, the interactions can induce changes in the overall shape of the binding site, as these different charges are "neutralized" against each other, or the two molecules adjust themselves for a better fit. This can sometimes result in the exposure of and otherwise hidden amino acid that can cause some further interaction to occur. There are also ways in which an amino acid nearby in the structure might pull electrons away from some part of the ligand, changing the properties of the molecule in a way that might cause it to break a bond. Breaking the amino acid chain in the ligand can then cause the other interactions holding it to the receptor to change, making the two parts no longer compatible with the receptor, allowing it to release .

I am leaving a whole lot of stuff out, but this is an idea that I find to be easier to visualize .

There are some types of locks which use and arrangement of magnets. The north and south poles of the different magnets are set up in a pattern that is complementary to the arrangement in the magnetic key. And so when you put the key next to the lock it can open, but if you put the wrong key next to the lock it will not be able to bind correctly. This is actually not a bad way to look at the interaction of receptors and their ligands or enzymes and their substrates.