One of the biggest barriers to enjoying classical music I think, is the names of pieces. For people just getting started with classical music the nomenclature can seem intimidating, arcane, and perhaps even arbitrary. And, unfortunately, there's a certain (small) segment of the classical audience that, like a grammarian, loves to correct any slight error or omission in a work's title.
Why not just call a song a song?
The reason why compositions have the titles they do is because, for the most part, the pieces aren't titled. Instead, they are generally referred to by the type of composition they are.
So while "song" pretty much covers anything in the realm of popular music, in classical music it would generally only refer to a work for voice and piano. Is it for violin and piano (with no singing)? Then chances are the composer calls it a "sonata." A "concerto" is usually for a solo instrument with a backing ensemble, while an "oratorio" is understood to be a piece for vocal soloists, chorus, and instrumentalists.
So the generic name for a work (whether assigned by the composer or not) is pretty important to identifying the piece. "Beethoven's Fifth" doesn't help much. Do you mean his fifth symphony, or his fifth piano concerto? Or perhaps his fifth string quartet, or even his fifth piano sonata? Knowing the right type of composition helps tremendously.
An Opus is more than a penguin
Imagine if, say, Led Zeppelin had given no titles to any of their songs. And let's say that they also didn't title their albums. How would you know which song you were listening to? One way would be to refer to the album by number (actually, Led Zeppelin isn't that bad an example -- their first four albums are numbered).
So then the proper name for what we know as "Stairway to Heaven" would be Led Zeppelin Song 4, Album 4. That's pretty much how it works in the classical world, too. Many composers published collections of music, similar to the concept of a record album. These usually have opus numbers. "Opus" comes from the Latin for "work" (notice how often classical compositions are referred to as "works").
So the first work, or collection of short works a composer has published is their Opus 1. You can get sometimes get a good idea of how prolific a composer is by looking at their opus numbers.
Consider Alan Hovhaness' Symphony No. 60, Op. 396, "To the Appalachian Mountains." Whether you look at the symphony number or the opus number, it's clear Hovhaness wrote (and published) a lot of music!
Key is key
So opus numbers are important, as are piece numbers within the opus. But why are keys always referred to? Well, they help further differentiate the work. Take Chopin's collection of Ten Etudes, Op. 10. Some of these etudes (or "studies") are written in different keys.
So you could just refer to the Etude in E-flat major, Op. 10 and that would be fine -- there's only one in that set. But you'd be in trouble if you talked about the Etude in C major, Op. 10. Because there are two. Do you mean Etude No. 1, or Etude No. 7? So that's why on the air we refer to it as "Chopin: Etude No. 1 in C major, Op. 10."
Composer, composition type, key, number in the set, publication number of the set. That's really what's behind most titles. And as long as it's clear which piece you're referring to, you don't have to be pedantic and include everything (although we usually do on air for clarity).
"Beethoven: Symphony No. 5 in C minor, Op. 67" is technically correct. But "Beethoven's Fifth Symphony" is equally clear.
That way there's no confusion.
But wait -- what about all that other stuff?
Don't worry -- I'll cover that in upcoming posts. Next time we'll talk about catalog numbers. Most composers have them, but they're only used widely used for some. I'll explain why.
The Naming Game, Part 2: Cataloging Chaos
The Naming Game, Part 3: Tilted Titles