Health codes are divided into three states: green code, yellow code and red team. The green code indicates health, and the yellow code and red team indicate the need for isolation. Among them, the yellow code is isolated for seven days and the red code is isolated for fourteen days.
The principle of health code is that big data detects your whereabouts and dynamics. If you have come into contact with a case or suspected case, it will change from a green code to a yellow code or a red team.