Sentence:  <WSD>QED</WSD> is the theory that explains how electrically charged particles, like electrons, interact with each other and with particles of light (photons). [...] Pretty much everything else – certainly everything you see and feel around you – is explained at the deepest known level by <WSD>QED</WSD>. Matter, light, electricity and magnetism – it is all <WSD>QED</WSD>. 
Meaning of the word marked with <WSD> tags:  ("Partial") (nocap=1)