Cross Join

Essentially a Cross Product

FROM courses, enrollment; 

Inner Join

SELECT column_name(s) 
FROM tablel
INNER JOIN table2 ON table1_column_name = table2_column_name; 

The = is the join condition.
The default JOIN Method

Left Join

Full Join

The full outer join which guarantees that all rows from each table will appear in the output.

Natural Join

When the same column name match, the join the table