Option sets are one of the data types available. An option set defines a list of options. When an Option Set is displayed on a form, it uses a drop-down list control.
An option in an Option Set is a key-value pair, a text label, and an integer value. The integer value is stored in the field on the record and the label is stored in metadata.
There are two types of option sets: Global and Local. Global option sets are separate components in your solution that you can reuse on multiple entities and fields. Local option sets are defined for one field. The Maker Portal defaults to creating global option sets.