What is a Hong Kong health code account?

According to the information about prevention and control regulations in mainland China and Hong Kong, Hong Kong Kangma learned that the health code accounts in mainland China and Hong Kong are Hong Kong health codes, which are used to cooperate with customs clearance in Guangdong, Hong Kong and Macao. In the future, mainland Hong Kong residents can only go to Macau and Guangdong if they meet the four conditions of "Hong Kong Kong Kang Code" green code, COVID-19 test results are negative before departure, and COVID-19 vaccination and quota reservation have been completed.