Copyright:
* Original Song: If the song is still under copyright, you need permission from the copyright holder (usually the songwriter or publisher) to use any part of it. They might grant you a license for a specific use, like "fair use" for educational purposes.
* Public Domain: If the song is in the public domain (copyright has expired), you can usually use it freely, but it's still good practice to cite the source.
How Much is "Too Much"?
* Parody or Commentary: You can often use more of a song if you're creating a parody or commentary on the original. This is considered "transformative" use and falls under "fair use" guidelines.
* Inspiration: If you're just using the song for inspiration, like a melody or chord progression, you might be able to use more, but you need to make sure your work is original and not simply copying the song.
* Quotes: A short quote, like a phrase or a line, is usually fine, especially if you're analyzing the lyrics or highlighting a specific idea.
Ultimately, it comes down to how much of the song you're using and how you're using it. If you're unsure, it's always best to err on the side of caution and get permission from the copyright holder.
Here are some things to consider:
* Purpose of your work: Are you using the song for entertainment, education, or critique?
* Amount of the song used: How much of the song are you using? A few lines or a whole verse?
* How transformative is your use? Are you changing the song in a significant way, adding your own interpretation or commentary?
Remember, even if you're allowed to use a song, you should always credit the original artist or songwriter!