Dealing With User Entering a Script

I dug back to see where I git the idea of using htmlentities() on user input. This came from the book Modern PHP and deals with a user entering in a text box something like: <script>window.location.href='http://example.com';</script> Is there a better way of dealing with this? For context, I am creating a user registration field and there is a textarea field for their bio. Thank you! -- Stephen