Your tables can participate in three types of relationships, and the picture shows them.
You have a one-to-one relationship when a single record in one table is related to a single record in another table, and vice versa. For example, one specialized file server may have just one repair technician.
You have a one-to-many relationship when one record in a table is related to many records in another table. For example, one employee can use many assets, such as a computer, chair, and desk.
You have a many-to-many relationship when several records in one table are related to several records in another table. For example, your company probably owns a large number of computers, and you may use several technicians to maintain those computers. Many technicians can be responsible for many computers.
One-to-many relationships are the most common type in a database. The others are fairly rare, and you won't use any during this series of courses. However, we will show you the basics of how to create them. For more information about them, see the links in the Quick Reference Card at the end of this course.