It's optional to set the filenames for images and other assets you upload, and I recommend that you get into the practice because there are benefits for SEO and your credibility.
Viewing entries tagged
Whether someone views your website on mobile, tablet or dekstop (or anywhere), Squarespace automatically adjusts how your pages display to make them look best for that environment.
"But doesn't that jack up my images?"
Because what parts of an image get cropped out and which ones show changes by environment.
BUT, some good news: you can use focal points to guide Squarespace in what part of each image to display, AND you can preview the look in mobile/tablet/desktop in your browser! No need to actually pull out all three devices and try separately.