Dangerous, poisonous, stay away, death and other icons. Of course, you can also design one yourself based on the characteristics of "concentrated acid and concentrated alkali drugs". The icons are mainly pictures so that everyone can understand them. For example, if there is a big bun on the plaque of a bun shop without any words, people will know that it sells buns. That's it. Icons are mainly used to convey the meaning to everyone more clearly...a little suggestion for reference.