Antihydrogen is the antimatter counterpart of hydrogen. Whereas the common hydrogen atom is composed of an electron and proton, the antihydrogen atom is made up of a positron and antiproton. Antihydrogen began to be produced artificially in accelerator experiments in 1995, but the atoms produced had such "hot" velocities as to collide with matter and annihilate before they could be examined in detail.

The standard symbol for antihydrogen is H. When spoken, it is usually pronounced "H-bar".

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