Outer Join
In plain terms
A join that keeps unmatched rows from one or both tables.
Going deeper
An outer join (left, right, or full) returns matched rows plus unmatched ones, filling gaps with nulls. It preserves rows lacking a match.
Under the hood
LEFT keeps all left rows, RIGHT all right, FULL both; useful for finding missing relationships.
Examples
Finding customers with no orders, LEFT JOIN, reports with optional data.
Think of it like...
Like an invite list showing every guest, marking those who didn't RSVP as blank.