There are lots of little strange phenomena on the Internet that just exist but have no apparent name. Have you ever wondered what it's called when a page loads all the visual elements but then rearranges them at the last second when you go to make a selection, causing erroneous inputs? I'm still not sure what the term for that is exactly, but there is a term for different loading icons that pop up while you wait for a page to fully render.
Conventionally, you'll visit web pages and be greeted with a load spinner of one style or another until all display elements are ready to take their seats and present the content to you. It turns out there's another style that's less commonly used, known as the skeleton screen. This is where the page is displayed in full, but the content is replaced with "bones" or markings that are meant to preemptively reflect where content will show up when it finishes loading.
Some people hate it; others love it. It's cited as being faster and more convenient, and if nothing else, it forges the effect of being faster even if it really isn't because it makes visitors feel as though the page has loaded before it actually does. I'm not one to discredit placebo - I think it's a mighty fine and perfectly honest way to streamline the user experience. However, I have to agree with one point against skeleton screens: If utilized inefficiently, they can be disorienting once the actual content loads, leading viewer's eyes to the wrong places and generating frustration.
There seems to be a great divide between developers of one sort and another, and it comes down to what type of site you're running. The traditional spinner effect is tailored more to web pages that display graphical content since the "bones" of a skeleton screen are meant to be placeholders for text that hasn't loaded yet. Your mileage may vary, and there are a handful of studies you can check out. However, it's worth keeping in mind that Google and Facebook seem to prefer this style of load placeholding, so take a page from the best and consider giving your website a boost.