There are insanely confusing collections of Johann Sebastian Bach preludes that absolutely destroy my brain if I try to keep them straight. For instance, there is a collection of 12 of them called “12 Little Preludes” and another similar collection of six of them called “Six Little Preludes”.
There is no logic to this and I even made an entry on my website about what a prelude really is.
These collections are simply phenomenally stupid. A few clowns simply picked a bunch of preludes, called them “little”, got the chronology wrong and made horrible choices in the order and mood. All this and so much more contributes to a horrible mess that drives me nuts.
All you need to know is that Bach wrote a bazillion number of preludes, and the quality of them ranges from good to excellent to superb.
The BWV numbers are simply an attempt to put all this music in chronological order. Those letters are a German abbreviation for “Bach Works Catalog”. This catalog is better than nothing but can easily lead to the assumption that we have a very good idea about when Bach composed all his music, and that is an illusion for the most part.