Opus number

Okay kiddo, so you know how musicians write songs and classical pieces? Well, sometimes they write a lot of them, like A LOT. So they need a way to keep track of which piece is which. This is where a special code called an "opus number" comes in.

Think of it like how you might name your drawings that you make. If you draw a picture of a cat, you might write "Cat Drawing #1" on it so you know it's your first cat drawing. Musicians do something similar with their pieces of music.

When a composer writes a new piece, they give it a special number called an "opus number." This helps them keep track of which piece is which, so they can easily find it or talk about it with other musicians. The number is usually written on the top of the sheet music for the piece, and it tells you which piece it is in the composer's collection.

So in summary, an opus number is a special code that musicians use to keep track of their compositions, so they can easily find and talk about them with other musicians.