All the entities are enclosed within rectangular bracket and relation between them are shown by diamond shape. All the attributes are shown with a elliptical shape.

The different relationships are shown as:

One-to-One is 1-1

One-to-Many is 1-n

Many-to-One is n-1

Many-to-Many is n-n

All the unique entries can be termed as a primary key and when represented as an attribute a line is drawn below them to state that they hold a unique value.

https://media.cheggcdn.com/media/dd4/dd4caf49-3eab-4457-8136-b8aea3754eba/phprSlEdq.png