How do you know if a song is copyrighted?

The easiest shortcut, though maybe not 100 percent foolproof for a major legal case but totally fine for school, is to check the date. In the US, anything published before January 1, 1926, is generally in the public domain and totally free to use. Anything created or recorded after that date is almost certainly copyrighted. The term is super long now, typically the life of the author plus 70 years, so almost all modern music is locked down. If you need something free, look for very old jazz, ragtime, or classical pieces where the composer died ages ago.

Don't overthink it for school. Just look at the source you're getting it from. If you download it from a site that says "stock music," "non-copyrighted library," or "music for video projects," it usually comes with a clear license that says something like "Free for non-commercial educational use." If you're pulling the song from your Spotify playlist or a CD you own, it's definitely copyrighted. They key for an assignment is showing the teacher you thought about the rights, so just use music from a site that specifically advertises its music as being available for this kind of use.

I learned this the hard way when I tried to use a clip from an older movie soundtrack in a video project a few years ago. You don't know it's copyrighted until someone tells you, but you should assume it is. Every song that exists, provided it was written down or recorded, is automatically copyrighted the second it's created. Registration just makes it easier to enforce. The only real way to "check" is by searching those ASCAP/BMI databases the first user mentioned, or seeing if a free music site specifically offers it without needing a license. If you can buy it on iTunes, it's copyrighted. Period.

Honestly, for a school assignment, the simple rule is: If you recognize it, it's copyrighted. If it's a song by Taylor Swift, The Beatles, or even a smaller band from the last 50 years, assume someone owns it and will want to be paid if you use it commercially or share it publicly. It's way easier to just look for "royalty free music" or "Creative Commons license" tracks on free music archives. Save yourself the headache of trying to track down a publisher.