The primary purpose of SSL encryption (Secure Sockets Layer) is to protect data as it is transmitted over the internet. It creates a secure connection between a web server and a browser, ensuring that any data exchanged remains private and cannot easily be intercepted or tampered with by third parties. SSL achieves this through encryption techniques, which encode the information in a way that only the intended recipient can decode it. Additionally, SSL provides authentication, allowing users to verify the identity of the website they are communicating with, reinforcing trust in online interactions.