In this video, we’re going to talk about the entity-relationship model. That’s a tool used by developers to design databases. 1. Okay, let’s go! Open up the gleek.io app https://www.gleek.io in your browser. 2. We’ll use Chen notation to create our example diagram. So each of the three basic elements in the model – entity, attribute, and relationship – is represented by a shape. An entity is a rectangle, an attribute is an oval, and a relationship is a diamond. 3. Let’s imagine that we’re designing a user database for an online multiplayer game. 4. We add the player entity by creating a rectangle with the word player inside it. 5. Our database needs some basic details to function. We’ll need the player’s email address, name, nickname, password, location, date of birth, and signup date. Each of these is an attribute. We represent attributes with ovals. 6. Our database records the player's name as first name and last name. That’s two simple attributes combined to create a composite attribute. Remember that you can always break a composite attribute down into two or more simple attributes. 7. That gives us our entities, but what about relationships? We want to let our players become friends with each other. We use a diamond to represent the friend relationship between players. So now you have all three of the basic elements of an entity-relationship diagram – entity, attribute and relationship.