asdf in web development and beyond

You got it right. The asdf sequence as it may seem at the first glance is a very handy tool. When editing HTML, PHP or other type of code, frequently you need to pause your work and remember the current place in order to copy something from somewhere (maybe from the same big file) and then quickly go back and paste it right where you were focused before. Some people use bookmarks, others remember it. But remembering requires a minimal effort, when the "autopilot mode" is desired.
The quickest and most effective way to do that, is typing asdf. This does two good things to you:

• First, as you already guessed, it leaves a bookmark. So coming back is just as easy as pressing Ctrl-F and then stroking the magical asdf.
• Secondly, if you're editing a code which is compiled, then the compilation won't succeed, which means, you'll never forget to come back to this bookmark.

Finally, you can always use similar sequences like zxcv or qwer etc., to add more reminders as required.
So happy coding and asdfing!