DISCLAIMER: I am not a lawyer, and this post should not serve as official legal counsel. You should always seek the advice of a certified legal professional.
All photographers and clients enter into a contractual agreement before a session or event. This legal document can be very intimidating at times!
One of the more confusing concepts included in a typical photography contract is the concept of usage rights versus copyrights. At times, clients ask if they can have the copyright. They paid for the photos, so they should own them...right? Well, it's actually a little bit more complex than that! When you work with a photographer, you're actually purchasing a service - which is something you can never actually "own."
Confused yet? Don't worry!
Here it is broken down as simply as possible:
Usage rights are rights granted to an individual by an artist to use something for a specific purpose and for a particular period. For example, I give usage rights to my clients to print photos to display for personal use/wedding invites/etc. or to share on social media as much as they'd like.
Copyright is the exclusive legal right, given to an individual to edit, print, sell, publish, distribute, etc. As soon as a photographer (or anyone for that matter) clicks the shutter on a camera, they automatically own the copyright to that image.
Unless you have permission from the photographer, you cannot create derivative works from the photographs. In other words, you can't edit the photos or claim credit for them. Just because you purchase a service, does not mean that you have purchased the copyright.
Hardly any photographers give the copyright to the photos, and if they do, they usual cost hundreds and hundreds of dollars. (Some photographers claim the copyright is included in their packages, but it's really not. Transferring copyright is a pretty involved legal process!) Copyright infringements can actually result in civil and criminal penalties, so they should be taken really seriously.
Here’s an analogy in case the above is still confusing: An author owns the rights to their book because it prevents people from changing it and plagiarizing it, but people are still allowed to post about the book, read it, buy it, post pictures of it, post quotes from it, etc. as long as they say site the author and the novel. It's the exact same thing as photography copyright. Clients are allowed to post all the pictures all they want, print them all they want, but they’re not allowed to sell or claim them as if they were their own intellectual property. It would essentially be the same thing as trying to sell a Harry Potter book and say you wrote it because you own that copy of the book.