So I've thought of a name for something, but cannot decide on how I should write it. In School, I vaguely remember someone saying "when you want to say something as one word, when it's really two words, then you hyphenate them", which leads me to believe I should be writing it like "Side-note". But How should you really write it, when it is going to be the name of something?
Are Sidenote, Side-note, and Side Note all correct? Which version should I use?