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We review advances in optical precision spectroscopy of atomic hydrogen achieved at Garching and Paris since the first symposium on the Hydrogen Atom at Pisa in 1988. The work at Garching has been focused on measurements of the 1S—2S and 2S—4S two-photon transitions in atomic hydrogen and on the isotope shift between hydrogen and deuterium. The Paris experiments have been directed at the 1S—3S and...