An SSL (Secure Sockets Layer) certificate is a digital file that verifies a website's identity and encrypts all data flowing to or from it, preventing unauthorized access. Encryption scrambles data into an unreadable format, which can only be decrypted using the proper key - the certificate. There are three main types of SSL certificates, linking to a domain, business, or both. This serves as an electronic "passport" establishing an online entity's credentials. When confidential information is sent to a web server, the user's browser accesses the server's digital certificate, verifying the website's identity and establishing a secure connection. The certificate includes the holder's name, serial number, expiration date, public key, and digital signature.