Cruft is a computing term–
In computer coding, cruft is the buildup of useless or redundant programming language, usually caused by incomplete editing, often resulting from tight deadlines. Let’s say you’re writing a program to automatically email a response to someone who leaves a comment on your website. You have two ideas as to how to go about this. You try one, but you’re not happy with the way it works. So you disable the first try–you don’t delete it, just in case your second try is worse–and try plan B. Plan B works great, so you save it, and you’re on your merry way. But that first attempt is just sitting there in the code, not doing anything, but taking up space.
The remnants of that first attempt is cruft. The program will work, and the end results may be just as effective as if you go back and get rid of all that redundant code. And that code just sits there, deactivated, taking up a small amount of space on someone’s hard drive, causing your website, or your computer, to run just the tiniest bit slower. A little bit of cruft is no big deal. But if too many of your programs have tiny bits of cruft, the cumulative effect can be noteworthy.
In creative writing the same process occurs. Let’s say you decide you need to delve into your protagonist’s reason for doing what she does. So you write a scene with her psychologist. The scene is well-crafted, and you love how the the snappy dialogue turned out–it’s actually one of your favorite scenes in the story. But now that you’ve moved on, you realize that her motivations are well laid out in the action of your story. But you don’t want to cut the scene because you’re proud of it–especially the great dialogue.
That scene is now cruft. It’s something that isn’t advancing your story–just taking up space. Now of course, this is a simplistic example. Maybe that scene still has a purpose. Maybe the fact that she can open up to her therapist but not her girlfriend is helpful to the story.
When editing, determining what is cruft and what still has purpose is one of the most difficult skills to develop. It’s only the most useless of description or scenes that has no purpose whatsoever. The harder line to walk is to know whether the bit of story is important enough to the plot, or the character development, or the texture of the writing to keep it.
It’s the difference between bloated writing, and tight, crisp prose.