By using joins, you can retrieve data from two or more tables based on logical relationships between the tables.
I’ve always found it easier to correlate them with sets and learn the concept
Considering two table A and B, the join operation can be thought of as analogous to below corresponding set operations between two sets A and B
CROSS JOIN - Cartesian product of A and B
INNER JOIN - A intersection B
LEFT JOIN - A union (A intersection B )
RIGHT JOIN - (A intersection B) union B
FULL JOIN - A union B