Britney Spears sold her music catalog. What does that mean?

By now, you've probably heard that Britney Spears sold her entire music catalog for $200 million. And she's the latest celebrity in the last couple of years to sell part or all of their catalog from Kiss to Justin Bieber, even Katy Perry. But what does it mean to sell your music catalog.Well, that is when you sell part or all of either your publishing rights, your master recordings to a third party like an investment fund or a music publisher. But why would anybody want to sell their music catalog. I caught ...