From Latin 'afficere' (to act upon), sharing root 'facere' (to do) with 'effect,' 'defect,' and 'infect.'
To have an influence on; to produce a change in; also (archaic/formal), to put on a pretense of or assume artificially.
From Latin 'afficere' (past participle 'affectus'), meaning 'to do to, to act on, to have influence on,' composed of 'ad-' (to) and 'facere' (to do, to make). The PIE root behind 'facere' is *dʰeh₁- (to put, to place, to make). There are actually two distinct Latin verbs that converged in English: 'afficere' (to influence) and 'affectāre' (to aim at, to aspire to, hence 'to put on
The confusion between 'affect' (verb: to influence) and 'effect' (noun: a result) is one of the most common errors in English — yet both words come from the same Latin root 'facere' (to do). 'Affect' is 'to do to' (ad- + facere), while 'effect' is 'to do out of, accomplish' (ex- + facere).