[] brackets in sql statements

Question

What do the brackets do in a sql statement?

For example, in the statement:

insert into table1 ([columnname1], columnname2) values (val1, val2)

Answer 1

Anything inside the brackets is considered a single identifier (e.g. [test machine]. This can be used to enclose names with spaces or to escape reserve words (e.g. [order], [select], [group]).