I’ve heard it mentioned in one Youtube video, and so far haven’t found something that covers this concept fully. What are Gestalt principles? Heard they’re key for UX but don’t get it.

Okay. Good question and proper approach here. I think I can answer it. Gestalt = how brains group elements. It includes:
1. Proximity: Buttons near search bars = assumed relation.
2. Continuity: Aligned carousel dots imply flow.
3. Figure/Ground: Dark mode’s text-background contrast.
I redesigned a checkout flow using proximity—grouped fields into ‘Shipping’ and ‘Billing’ sections. Errors dropped 30%. Brain hacks > tutorials. And here you can check some gestalt design examples