SSL is a secure socket layer, an encryption-based Internet security protocol originally developed in 1995 to guarantee privacy, authentication, and data integrity in Internet communications. SSL is the predecessor of today's TLS encryption. Websites that implement SSL/TLS have urls that contain HTTPS instead of HTTP.

How does SSL/TLS work? To ensure high privacy and security, SSL encrypts data transmitted over the network. Anyone trying to intercept the data can only see garbled characters that are nearly impossible to decrypt. SSL initiates a "handshake" authentication process between two communication devices to ensure that both devices are secure and correct. SSL also digitally signs data to ensure data integrity, verifying that the data has not been tampered with before it reaches the intended recipient. SSL was updated several times, each iteration more secure, and in 1999 SSL was updated to TLS.

In the beginning, data on the network was transmitted in plain text, which could be read by anyone who intercepted it, and there was no hiding at all on the Internet. The birth of SSL solves this problem by encrypting all data transmitted between users and web servers, protecting user privacy. Are SSL and TLS the same thing?

SSL is the predecessor of TLS, the two protocols are closely related and many people will confuse the two certificates, many users are still using SSL instead of TLS, and some users use the SSL/TLS encryption term, mainly because SSL is still very well-known.

SSL has not been updated since the release of SSL 3.0 in 1996, is now considered deprecated, has multiple known vulnerabilities, and security experts recommend discontinuing its use. Most modern browsers no longer support SSL. TLS is the current encryption protocol, and although many still refer to it as "SSL encryption," TLS has become an industry standard.

What is an SSL Certificate? An SSL certificate (technically known as a TLS certificate) is proof of a website's identity and is stored on a server. One of its important pieces of information is the public key of the website, which the user device can use to establish a secure connection with the Web server. Certificates are issued by a Certificate Authority (CA).

Types of SSL certificates: Single-domain certificate: applies to only one domain name. Wildcard certificate: applicable to a domain and its subdomains; Multi-domain certificate: applies to multiple unrelated domain names.

SSL certificates also have different levels of authentication: Domain name authentication: the simplest and cheapest, and only needs to prove control of the domain name; Organizational verification: CA directly contacts applicants to provide higher trust; Extended verification: Full background checks are required to provide the highest level of confidence.