To log in is to enter your name and secret word to open your account. Log in first.
The phrase comes from the ship's log, where arrivals and departures were written down. To log in is one word as a noun and two as a verb, which catches everybody out.
1phraselog inTo enter your name and secret word to open your account.
“He could not log in for three days and nobody could say why.”
log in is an action.
Also accepted in games: log on, sign in
By analogy with clock in; the term appears in computing from 1963.
By analogy with clock in. First use of the term appears in 1963 in the publication Compatible Time-Sharing System from the MIT Computation Center.
Etymology from Wiktionary, CC BY-SA
Practised in Everyday Verbs