tl;dr:"IDN, International Domain Names, is the concept that lets us register and use international characters in domain names, and by international we of course mean characters outside of the ASCII range. Recently I have fought some battles against IDN and IDN decoding so I felt this urge to write a lot of words about it to help me in my healing process and maybe mend my scars a little. I am not sure it worked but at least I feel a little better now."