Modals contain smaller pieces of additional content while maintaining the context of the rest of the page, covered by a transparent overlay.
The confirmation modal confirms the end result of an action such as Destructive / Irreversible actions / Affirmative actions.
Input/edit modals allow people to change data or settings without leaving the page. They support the ability to edit up to 3 fields. Any more becomes crowded and a new page or Isolation modal is preferred.
An input/edit modal may also be used to present data-intensive information such as a list of employees where the information modal is inappropriate.
If data will be lost by dismissing the modal unintentionally, consider autosaving.
Information modals assist with education. They’re user triggered. They may be relative to a deeper level of information. May be useful for first time users. Heavily optional. Visual aid is good. Primary action optional.
Here are some examples of other existing design systems: