Why do SQL Server table names add square brackets?

I just installed the Microsoft SQL Server 2000 Human Edition and found out how the SQL statements are different from the standard. For example, I use the simplest query statement "SELECT * from user" query table user, the result it hints syntax error, and then the system automatically corrected me to "select * from [user]", the query was successfully executed.
This means that adding square brackets to the table name is the correct format.

This is not required, but if the table name or field name references a keyword in SQL Server, the database does not recognize whether this is a keyword or a table name (or field name) that must be added.

For example, a table named User,user is a keyword in SQL Server, so you have to do this when querying:

SELECT * from [user];

Similarly , if user belongs to the field name, also add, if otherwise will be error.

SELECT * from table name where [User]=1;

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Because "user" is a keyword reserved by SQL Server, a "select * from user" query will prompt for syntax errors. Add the number to declare that it is not a reserved word.
If the table name is not a keyword, such as company, then use "SELECT * from Company" is no problem, do not add brackets

Why do SQL Server table names add square brackets?