Nightclubs and large events, like some football matches, will only be able to allow entry to people who can show they have had two doses of a Covid vaccine.
The scheme came into effect on 1 October after MSPs voted to back the proposals.
Businesses were given a 17-day "period of grace" to allow venues time to test out their procedures.
People who have had two vaccines in Scotland can download or get a paper copy of a certificate with a QR code.
Everyone over the age of 18 must now show - if asked - that they have had both doses of the vaccine before they are allowed entry to certain venues and events. These include:
The scheme requires venues to put in place a "reasonable system" to check the status of customers, with certain exemptions on medical grounds.