https://www.techradar.com/news/best-canon-lenses

Ultra-wide zoom lenses are the thick end of the wedge, at least when it comes to viewing angles. With zoom ranges starting at just 8mm for APS-C format lenses, and 11mm or 12mm for full-frame, you can shoehorn vast areas of a scene into the image frame. It’s great for shooting sweeping landscapes or architecture, and arguably even more useful when shooting indoors, where space is limited and your back’s up against the wall.

Another key attraction of ultra-wide lenses is that you can create images with extraordinary perspective effects. Get in close to the main subject in a scene and you can massively exaggerate its relative size, against a shrunken and rapidly receding background. Parallel lines appear to converge at alarming rates and shots generally get a proper wow factor.