Update sets are used in ServiceNow to move functionality from one instance to another. If you are making some changes in a development instance which you would like to later move to a production instance, then update sets are recommended.

An update set captures changes that you make to an instance, inside the update set, while they are being made. Once all the changes that you would like captured are finished, the update set is complete and is ready to be moved to another instance. When moved to another instance, the update set can be previewed to check that the changes are compatible with the instance and committed to apply the changes.

Before making any changes that you intend to move to another instance, your first task should be to create a new update set to contain those changes. Before you start making changes, ensure that you are working inside the update set. Once the updates are complete, complete the update set that is ready to move to another instance.