This symbol indicates that the purpose is expressed in a wide range through instructions and formulas. English name: brace, also called curly braces.
Parentheses are symbols used to specify the order of operations.
The earliest bracket is the bracket "()", which appears in 1544. It was not until the17th century that the brackets "[]" appeared in the works of Varis (161703) in England, and the enclosed line was changed from Vedas 159 1 year. By 1629, Kirad in the Netherlands had adopted all brackets, and it was used in the world after18th century.
With the deepening of mathematics learning, all brackets can be replaced by "()", which looks very convenient and can avoid the situation that there are too few bracket styles.
In elementary number theory, it is used to express the greatest common divisor, for example, (11,148) = 37.