Whenever we need to retrieve data from two or more tables we can use Joins.The output of join is matching records from both the tables.
In Teradata database we have Optimizer to determine which type of join strategy to be used and type of indexes to be used.
In General, Most common types of joins are the following.
Inner join (Self join)
Outer Join (Left outer join, Right outer join, Full outer join)
Cross join (Cartesian product join)