An SSL (Secure Sockets Layer) certificate is a digital certificate that helps secure the communication between a user's web browser and a website's server. It does this by encrypting the data transmitted between the two parties, ensuring that it cannot be easily intercepted or tampered with by malicious actors.

SSL certificates are commonly used to establish a secure and encrypted connection, often denoted by the "https://" in a website's URL and a padlock icon in the browser's address bar.