1, Mathematics and Science: In mathematics and science, brackets are usually used to indicate closed intervals. For example, [a, b] represents all real numbers greater than or equal to A and less than or equal to B.
2. Programming: In many programming languages, parentheses are used to create arrays and access array elements. For example, in JavaScript, let arr = [1, 2,3]; Create an array with three elements, and arr[0] accesses the first element of the array.
Notes and supplementary notes: In writing, brackets are often used to insert notes or supplementary notes, for example, "He works in Beijing [the capital of China]".
4. Citation and reference: In academic writing, brackets are often used to insert quotations or references, such as "according to [XXX]".