Good! You may be wondering what the difference is between tables and views. If they're so similar, why would we use views?

A view doesn't actually contain any data. Data is physically stored in tables. Each time you query a view, the table (or tables) underneath the view is queried to get the rows again. Views are also represented differently in ERDs:

There are many applications for views:

1. For security reasons, you may only want to expose a limited number of table rows or columns to a certain group of users.
2. You may want to create some calculated columns on the fly – e.g., to convert between the imperial and metric systems.
3. You may want to have a convenient way of working with aggregated columns without grouping the rows in every query you run.

In all of these cases, it's usually better to create a view than a new table. This way you avoid data redundancy and optimize disk space usage.

We'll explore these view uses in the following exercises.