Commercial Internet Exchange
The providers' own meeting point from 1991, built so commercial traffic could steer clear of the government backbone.
The NSFNET Acceptable Use Policy barred traffic that didn't support research and education. Providers with paying business customers therefore had a problem: their customers couldn't legitimately reach each other across the backbone. In 1991 PSINet, CERFnet and UUNET's AlterNet founded the Commercial Internet Exchange, an interconnect where members swapped traffic directly and without settlements.
The principle — providers meeting and exchanging traffic rather than paying a third party — underpins today's exchange points and peering. Not to be confused with the British conferencing service CIX, which shared the letters and nothing else.