From PIE *dheh1- (to put, to place) — sharing its root with Greek 'thesis,' Latin 'fact,' and even 'condition.'
Perform or carry out an action; used as an auxiliary in questions and negations.
From Old English 'dōn' (to do, to make, to act, to perform, to cause), from Proto-Germanic *dōną (to do, to place, to put), from PIE *dʰeh₁- (to put, to place, to set, to make). The same root produced Greek 'tithénai' (to put, to place), Latin 'facere' (to make, to do — from the related *dʰh₁-k-), Sanskrit 'dádhāti' (places, puts). The auxiliary use of 'do' in questions ('Do you
English is the only major Germanic language that uses 'do' as an auxiliary verb in questions and negations. 'Do you know?' and 'I don't know' are grammatically bizarre from a German or Dutch perspective — no other Germanic language requires an empty auxiliary verb just to ask a question. This 'do-support