What are the different types of SQL JOINs?

INNER JOIN returns matching rows from both tables. LEFT JOIN returns all rows from left table plus matching rows from right (nulls for non-matches). RIGHT JOIN is opposite of LEFT. FULL OUTER JOIN returns all rows from both tables (nulls for non-matches). CROSS JOIN returns Cartesian product of both tables. Self-join joins a table to itself. Each type serves different purposes for combining data across tables.