Today I'm going to settle a debate that comes up from time to time on The Magic Cafe and in other places. It's one of those questions that comes up frequently enough that I think, "Wow, we're a bunch of idiots," because as a sub-culture we haven't settled the issue yet. But now I'm going to settle it so the next time it comes up you can be like, "Oh, that's settled, let's shut up about it."
And that issue is: What is impromptu magic?
You would think we would have figured this shit out, given that it's a term used in magic advertising. But no, in fact, the definitions are so broad that virtually any trick you can think of will fit in someone's definition of impromptu. That's a shitty usage of the word when it can be used to mean absolutely anything.
No more. Here is what "impromptu" means in the context of magic.
An impromptu effect is one that requires no secret props or gimmicks of any kind and could be immediately performed with borrowed objects common to the performing environment.
There you go. So that's settled.
"no secret props or gimmicks" - When people say, "This trick is impromptu as long as you have a loop on your wrist." That is like saying, "That would have been consensual sex if she had just said 'yes' when I asked her to fuck." Or, "This dish is vegetarian except for the ground beef." You can't exclude the one thing that makes something NOT something and then claim that it is that something, except for that one thing you're excluding. Yes, I know that sentence is super confusing. For something to be impromptu then the only objects in play are the ones the spectator knows about.
"Immediately performed" - Meaning the objects in play don't require any secret preparation that can't be done in front of the audience. A full-deck stack would eliminate a trick from being impromptu, but one where a couple of cards had to be set-up or a card reversed without the audience knowing could be considered impromptu because these are "set-ups" that can be done in the process of performing.
"borrowed objects" - The items don't have to be borrowed. But for an effect to be considered impromptu, then everything could theoretically be borrowed.
"objects common to the performing environment" - In a way this broadens the definition of impromptu. Impromptu does not necessarily mean that it can be done anywhere at anytime. It's not a judgment on the practicality of a trick. For example, a trick that requires a secret extra penny would not be considered impromptu even though there's a good chance you already have one on you or could acquire one very easily. It's a secret prop, so that's not impromptu. On the other hand, a trick that requires a ukulele and a jar of mayonnaise can be impromptu if you could borrow those items and go right into the trick.
Impromptu does not mean that the trick "appears spontaneous." That is a stylistic performance decision on your part. It's not an inherent quality of a trick.
Impromptu does not mean that it doesn't require practice. The amount of practice something requires is unique to each performer. If you release a book test and the method requires the performer to have memorized the Bible, that trick still might be impromptu. Impromptu is a description of performance conditions, not an indication of the level of practice or rehearsal needed.
Again, we're talking about the usage of the word in magic and as a magic marketing term.
The purpose of defining the word so strictly is so we can actually use it and allow it to have some meaning. "Impromptu" is not a word that you should slap on a product and have it be meaningless, like "tasty" or "delicious." It should be something like "no dairy" or "this product contains nuts" or something that actually helps you make an informed buying decision.
Of course this is all predicated on my definition becoming universally accepted, which is unlikely because magicians would rather stumble around and not come up with anything useful than listen to me because I'm a bad man who uses naughty words. So unfortunately you can't just direct people who abuse that word to read this post.
However, we can trick those people. I've put the same definition up here and attributed it to Martin Gardner and Dai Vernon. Now we can use that as the official definition and move on with our lives.