Just what exactly does BWV mean?

One of my  pet peeves about classical music is how confusing the lingo and traditions can be for the anyone who's not a classical music junkie. When I was updating my site with information about the organ & voice concert I'm singing on in April, I encountered one of many cryptic terms: BWV. What on earth does this mean?

BWV stands for Bach-Werke-Verzeichnis, or Bach Works Catalog. Wolfgang Schmieder assigned numbers to J.S. Bach's compositions in 1950 for the cataloge Thematisch-systematisches Verzeichnis der musikalischen Werke von Johann Sebastian Bach (Thematic-systematic catalog of musical works of Johann Sebastian Bach). The numbers are assigned thematically (based on the opening musical notes or the main musical theme of the piece), rather than chronologically.

So, there you have it: one of the classical music world's mysteries revealed!