system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: When transferring money between banks, where is it when it is not in either account?

When I transfer money from one bank to another (whether by check or electronic transfer), there is always some period of time when the money is in neither account. Where is it? Who has it? Can they do anything with it (e.g. loan it out for an hour)?
gpt
It's still in the first account, but it's flagged by most computer systems as "not usable" to prevent overdrafting.  If there were some error and the transaction didn't go through, it would remain in the original account.

The "in between" state is there because most banks immediately tag the money as "gone" so that users can get a clearer picture of their finances.  And the "receiving" bank doesn't list the money in their system until it arrives, just in case there's a problem and the transaction doesn't go through.  This way, nobody accidentally spends money that they don't have.