This is one of the most frequently asked DBMS interview questions for freshers. Here is how to answer this. Entity: An entity is a real-world object with attributes that are just properties of that particular object. For example, a student can be an entity. This particular entity can have attributes like studentid, studentname, etc.  Entity Type: An entity type is simply a collection of entities with the same attributes. An entity type generally references one or more related tables within a particular database. An entity type can therefore be understood as a characteristic that uniquely identifies an entity. For example, an employee can have attributes such as empid, empname, and department.  Entity Set: An entity set is a collection of all entities of a particular entity type in the database. For example, a group of employees, a group of companies, and a group of people can be grouped into entity groups.