While this can be useful for providing you with quick and easy access to content, if a file or link is associated with the “wrong” application, then this feature can quickly become frustrating, as you may find yourself constantly closing applications that you didn’t even want to open in the first place. You see the same behaviour with links: if you click a link to a website, then macOS will load this website in Safari, and if you click a link to an email address, then macOS will launch the Apple Mail app. Whenever you double-click a file, macOS responds by opening this file in its default app. Whether it’s an MP3, a PDF, a word processing document or something more obscure, every file has a default application associated with it.