I’m going to show you how to create an entity-relationship diagram using crow’s foot notation. 1. Open up the gleek.io app https://www.gleek.io/ and select the entity-relationship option from the dropdown. An ER diagram shows entities, their attributes, and the relationships between them. 2. Let’s map out an online store to show how crow’s foot notation works. We’re going to simplify the store in our example and only draw four entities - customer, order, product, and discount code.