Where does asdf come from?
The QWERTY keyboard layout is the standard number and letter layout for computer keyboards. When the fingers are on the middle row for touch typing, asdf are the first four letters in order for the left hand. The letters go from the left pinky to the left index finger while the hand stays in place.
Additionally, since the majority of people are right-handed and therefore use the mouse with their right hand, the left hand is the one more likely to stay on the keyboard. So asdf can, for most touch-typers, be typed without having to move the hand.
The QWERTY layout has contributed to asdf’s popularity as filler text. When you just need to type something, for instance, to check if a post will work or to give an example of code, asdf is one of the easiest and fastest sequences to type. Evidence of the use of this sequence in filler text dates back to at least 1995, when it was typed in a Usenet post associated with programming.
Asdf is common in keysmashes. A keysmash is a collection of random letters typed out to express high emotion like frustration or, here, excitement: “I got the new Harry Potter book adjfkslskfjsla.” Generally, the longer the keysmash sequence, the higher the emotion. Keysmashes are frequently composed of middle-row letters because you don’t have to move the fingers up or down to access them.
Who uses asdf?
Asdf can stand on its own as a keysmash, but it’s more popular to use it several times. A related keysmash is asdfghjkl, which consists of all the letters on the middle keyboard row. This is another common sequence used to express the same meaning.
ASDF as an acronym is quite common, standing for, among other things, Association of Synchronous Data Formats and Air Self Defense Force. These should not be confused for the filler/keysmash meaning of asdf. One helpful way of differentiating is that, while acronyms are capitalized, the key sequence asdf is only capitalized as a means to express high emotion.
As a common filler text in online culture, asdf in part inspired the name of asdfmovie, a popular internet cartoon.
“my mom really made me rap humble for her bc she didn't understand what he was saying asdfasdf”
@lilatinaizzy Twitter (May 2, 2017)
“ASDF thank you so much kai im glad u liked it ”
@Yorlenisama Twitter (April 24, 2017)
Godspiral Reddit (January 4, 2017)