What you need to know before try Emacs

When it comes to Emacs, every programmer should have heard its name more or less. After all, Emacs has nearly forty years of history. However, many users abandon Emacs before comfort with it due to the steep learning curve. I understand their frustration, I also made many attempts before "skilled" in Emacs. After spend honey moon with Emacs for four years, I think I can share what I learn from Emacs and shed some light for newcomers.