Explain Subquery and state its properties?

Subquery – It is a query which is used when expressions are allowed and can be nested inside the main query like SELECT, UPDATE, DELETE or INSERT statements.
Properties:

• A subquery in the main query that has to be placed on the right-hand side of the comparison operator
• A subquery has to be placed parenthesis, in order to get executed first before the main query.
• It cannot have any order by clause.
• More than one subquery can be included in the main query.