What is a bond?

Atoms can be modelled as point positive charges with clouds of electrons around them. When two atoms come together close enough, a region of higher electron density forms between the two atoms. This means that there are more electrons in between the two nuclei than expected from bare atoms. Thus an equilibrium position is reached, which maximises 'gains' from proton-electron interactions and minimises 'loses' from proton-proton and electron-electron interactions. The arrangement when two atoms are at these equilibrium positions is what we call a molecule. And a bond is the region of heightened electron density between them. (I could include a 6-12 plot here).