Explain the difference between an inner join and outer join. Why is it important to understand joins ...

An inner join is a join that selects only those records from both database tables that have matching values and is the default join setting in Access. One or more fields can serve as the join fields and records with values in the joined field(s) that do not appear in both of the database tables will be excluded from the query dataset.
 An outer join selects ALL of the records from one database table and only those records in the second table that have matching values in the joined field. One or more fields can serve as the join field.
 Joins help you control which records will be displayed in the query dataset. This enables you to enhance your dataset even further to find the data that you want.

Very good answer