1. What is a sign?
Command signs are one of the important types of traffic signs, command signs instruct traffic participants to carry out commands such as: Go straight, slow down, go faster than the minimum speed, turn right, turn left,…
2. Classification of signs
Road signs in this Regulation are divided into the following 5 basic groups: prohibition signs; command signs; danger and warning signs; signposts; auxiliary signs, signs written in words.
Signs on highways and foreign roads must comply with the regulations stated in international treaties to which Vietnam is a member.
2.1. Group of prohibition signs
A group of prohibition signs is a group of signs that represent prohibitions that traffic participants must not violate. Prohibition signs are mainly circular in shape, red border, white background, with drawings or black numbers and writing representing the prohibition, except in some special cases.
2.2. Group of command signs
A group of command signs is a group of signs to signal commands that must be obeyed. Traffic participants must obey the instructions on the signs (except for some special signs). The signs are circular in shape on a blue background with white drawings that represent commands to notify road users.

2.3. Danger sign group
Danger and warning signs are a group of signs that let traffic participants know in advance of dangers on the road so they can proactively prevent them in time. The sign is mainly in the shape of an equilateral triangle, with a red border, a yellow background, and a black drawing depicting the event that needs to be signaled.
2.4. Group of signposts
A group of direction signs is a group of signs used to provide information and necessary instructions to traffic participants. Signs are mainly rectangular, square or arrow-shaped, with a blue background.
2.5. Group of secondary signs, signs written in words
The group of secondary signs and signs written in words is a group of signs intended to supplement the content of the sign group in clauses 2.1, 2.2, 2.3, 2.4 of this article or used independently.