Want to reprint a famous author’s writing on your website? You could get sued. Dropped a clip from a TV show or movie into your YouTube video? You could get sued. Have almost any identifiable song playing in the background of your Facebook video? Heck, you probably won’t get sued… but that’s only because Facebook will automatically take the whole video down within minutes of your posting.
And If you’re an app or software designer, there are even design patterns you can’t use because Netflix or Google beat you to it, and they have the patents to prove it.