Feynman diagrams provide a visual way to represent complex particle interactions and are an essential tool in quantum field theory.
In particle physics, Feynman diagrams are graphical depictions of the interactions between subatomic particles. The Feynman diagram for an electron-proton collision includes the exchange of a virtual photon.
In this image that we have here:
The particle's initial and final states are shown by the horizontal lines.
The exchange of a virtual photon (γ*) between the proton and electron is represented by the wavy line.