• 1)an invoice is written by one sales rep but a sales rep writes many invoices. 2)a vendor sells many products but a product is bought from one vendor. 3)an invoice has one or many products and a product is found on zero, one or many invoices. -Identify the entity -Identify the entity’s attribute -Identify the primary and foreign Keys -Identify relationship between Entities -Identify the Cardinality constraints -Draw ERD (Entity Relationship Diagram)