In many high-load projects, it is sometimes necessary to perform certain actions, for example, to process the data entered by the user. The processed data can sort tons of information, which takes more time. So the user does not need to think that the site is frozen and he could not exit the process during this period. This requires visual loading or a loader / preloader.
Now you can find many different options for animated loaders, but in most cases they have difficult logic and are rather problematic to apply, especially for a beginner.
This preloader is cross-browser and adaptive for Safary / Mozzila / Chrome browsers.
As always in my examples, I provide an archive link for downloading files. Which of the preloader to choose, you decide by yourself.