Well, think of it this way: there are several types of relations between objects - one to one, one to many, many to many. Imagine, lets say, i would like to represent a database model for your store. I will have a table "Clients" (with fields: ClientId[int, primary key], ClientName[varchar50], ClientEmail[varchar50]...etc ) and another table "Orders"(with fields: OrderId[int, primary key], ClientId[int, foreign key], OrderName[varchar50]... etc ). Now, here we come to the point why it is called "relational database": by creating different types of relations between tables you represent a highly cohesive model. This means that you create a certain record once, and from then on, this record is represented by an Id adn this way you save alot of space (the data type of integer is way smaller, compared to the repetition of the data). Here is one final example: in your model most likely you will have an "one-to-many" relationship between a client and an order, which means, that one client can have many orders, but one order cannot have to clients. There for, "Clients" table will be parent to "Orders", and they will have a relationship on "ClientId". Hope this helps. Feodor