Charge is a quantity carried by a particle that determines its participation in an interaction with other particles. A particle with electric charge has electromagnetic interactions; one with strong charge (or color charge) has strong interactions, etc.


It is a characteristic property of charges that they are conserved; they can neither be created from nothing nor simply disappear. For instance, when a positron with electric charge +1 (in suitable units) and an electron with electric charge -1 annihilate to give electromagnetic radiation, overall charge conservation is satisfied: Before the annihilation, the sum of the electric charges was 1+(-1)=0, and afterwards, when there is only uncharged electromagnetic radiation left, it is also zero.