You need an SSL certificate to:

Encrypt sensitive information (e.g., credit card numbers, login credentials).

Ensure data integrity, so data isn’t altered during transfer.

Authenticate the identity of your website, confirming to users they are connecting to the intended site.

Improve SEO: Search engines like Google boost rankings for websites that use HTTPS.

Build trust: Users are more likely to trust and engage with websites that display a secure padlock or "HTTPS" in the browser bar.

SSL (Secure Sockets Layer) was the original security protocol used to encrypt data between clients and servers. TLS (Transport Layer Security) is the successor to SSL and provides stronger encryption and security features. Even though SSL is often used as a term, most websites today actually use TLS certificates.

HTTPS (Hypertext Transfer Protocol Secure) is the secure version of HTTP, the protocol used to transmit data over the web. When an SSL certificate is installed on a website, the data is transferred using HTTPS, which encrypts the communication between the client (browser) and the server.

SSL certificates work through the use of public-key cryptography:

A browser requests a secure page (HTTPS).

The web server sends the browser its SSL certificate.

The browser checks whether it trusts the certificate.

The browser and server establish a secure connection using a session key.

All data transferred between the browser and server is encrypted.