Sometimes when you move your site to another server and the database has different charset (or something else mysterious happens), you may find some of your images broken cause of the weird characters in the names. To be on the safe side, it’s nice to sanitise the file names.
When installing, lets say, a WordPress, you naturally need to move the files to the server. It’s about ~100 times faster to move one big compressed file than a folder containing literally thousands of small files. But, you can’t unzip anything from your FTP client. Here’s all about zipping and unzipping.
Usually you would do the loading spinner as an animated gif, but it has it’s fallbacks. Gifs have no alpha transparency and for retina screens you’d need another double the size gif. Spinner.js has none of those limitations and is very customizable, plus it only weights 2KB when zipped. A loading gif I was using before weighted 20KB.