An Entity is an existing or real thing and we can also say that Entity is any singular, identifiable and separate object. In database management system we can say that Entity is collection of some attributes. for example a pen is an Entity which have some attributes related to the pen likes pen name, pen color, pen cap etc. It is also refers to individuals, organizations, systems, bits of data or even distinct system components that are considered significant in and of themselves and it is used in a number of programming languages/concepts, database management, systems design and other arenas. In ER-Diagram Entity is represented using for relationship and also used for describe the working of project.