Gestalt theory

The laws mentioned most regularly are the laws of proximity, similarity, closure, and the law of continuity.

A form is a very good example in which poor use of the Gestalt laws shows up very clearly. You work on the spacing between the labels and the answer fields in order to clearly define the question as an object. When several questions relate to the same theme, you can bring them together in a section by adding a graphic element that groups them. Without that, you can end up with a form that is harder to understand for the person who has to fill it in.

Yes, Gestalt applies to every medium. The theory describes the principles by which a human brain will interpret the different elements that make it up.

Typography and logotypes are elements that are entirely subject to the same Gestalt laws as all graphic elements. The handling of letter-spacing can affect the legibility of a typeface because of those laws. The same goes for the logotype, which relies to a large extent on Gestalt principles.