The notation we use in this book is crow's foot notation. We use rectangles to represent entities. For example, the following represents User entities and Team Entities:

And, we use a line to connect rectangles to represent a relationship. For example, Figure 5.3 represents the relationship between User entities and Team entities:

In this relationship, the symbol with double perpendicular lines on the left side means one and only one, and the symbol on the right side that is similar to a crow's foot means zero or many. It reads like this from left to right—Each user may create zero or many teams. And, it is like this when reading from right to left—Each team must be created by one and only one user.

Here are the relationship symbols in crow's foot notation: