When did people start using the corporate jargon "let's take it offline" (let's discuss that after this meeting in private)?
According to the Online Etymology Dictionary, the origin of online is from 1950:
online in ref. to computers, "directly connected to a peripheral device," is
attested from 1950 (originally as
on-line).
If the word offline in the jargon is the antonym of online as defined above, then the jargon cannot be interpreted literally. It is often used in meetings where people are all physically in the same room.
Best Answer
Warning: pure speculation.
It used to be that time spent connected to the network was very expensive. Back then, dealing with information to be processed offline was to use cheaper cycles to deal with that information. I most commonly hear this phrase in meetings, where a great deal of expensive engineer time is being wasted by details that only relate to 2 of the participants. Thus, taking the conversation offline is a metaphor for having the conversation on cheaper time.