explain the types of join in easiest way.?

Answer 1

Just a question of matching.
If you have the same values in two tables, inner join will display lines where there is a match with the two values. If not, inner join will display nothing.
On the other hand, left or right outer join will display all lines with a match and all lines of one table even if there is no match.
At the end, full outer join will display all lines of the two tables, match or not match.