Data types let you define the type of data you will store in a variable and, therefore, the type of data you expect whenever you update the data in that variable.
For example, if you have a variable that stores the color the user wants for the background, then the data type of the variable would be of type color. You will get an error if you try to store a value not of type color (for example, "#435647") in that variable.
If you have a variable that stores the name of a new To Do item, then the data type of the variable would be of type text, representing the name of the To Do item.
When you define a new variable, you can define the type of the variable on the right side.
Note that data types are used not just for variables but also to define schemas–or the data types and organization of larger sets of data–for data resources. There are fewer data types available for data resource schemas.