When the World Wide Web began to grow in the early 1990s, it was built largely without security in mind. Information sent between a user’s browser and a website traveled in plain text, making it easy to intercept. As online commerce and user accounts started to appear, this weakness quickly became a serious problem. The solution emerged in 1994, when Netscape introduced Secure Sockets Layer, better known as SSL. Its goal was simple but revolutionary: encrypt data in transit so it could not be read or altered by third parties.
The earliest versions of SSL were experimental. SSL 1.0 was never released due to major design flaws, and SSL 2.0, introduced in 1995, was quickly shown to be insecure. These early failures, however, laid the groundwork for a more robust system. In 1996, Netscape released SSL 3.0, a much stronger and more reliable protocol. SSL 3.0 became widely adopted and established many of the concepts still used today, such as certificate-based authentication and secure handshakes between client and server.
As the internet expanded beyond Netscape’s influence, the need for an open, standardized security protocol became clear. In 1999, the Internet Engineering Task Force took over development and introduced Transport Layer Security, or TLS. Although TLS was technically a new protocol, it was heavily based on SSL 3.0. Over the following years, TLS evolved steadily. TLS 1.1 addressed earlier cryptographic weaknesses, and TLS 1.2, released in 2008, became a long-standing backbone of secure web communication thanks to its support for stronger encryption algorithms. Despite this transition, the term “SSL certificate” remained in popular use, even though websites were now using TLS.
During the 2000s, the ecosystem around SSL and TLS certificates matured. Certificate Authorities became trusted third parties responsible for verifying identities and issuing certificates. Web browsers began shipping with built-in lists of trusted root certificates, forming the public key infrastructure that still underpins the web today. Different validation levels emerged, ranging from basic domain validation to more rigorous organization and extended validation, reflecting varying levels of identity assurance.
For many years, HTTPS adoption was slow, largely because certificates cost money and required manual configuration. That changed dramatically in 2015 with the launch of Let’s Encrypt. By offering free certificates and fully automated issuance and renewal, Let’s Encrypt removed one of the biggest barriers to encryption. Around the same time, browser vendors started marking non-HTTPS websites as “Not Secure,” pushing the web decisively toward encryption by default. HTTPS rapidly became the norm rather than the exception.
The modern era of secure web communication began in 2018 with the release of TLS 1.3. This version simplified the protocol, removed outdated and insecure features, and significantly improved performance. In parallel, certificate lifetimes were shortened to just over a year, reducing the risk posed by compromised keys and making automation essential. Transparency logs and stricter validation rules further strengthened trust in the certificate ecosystem.
Today, SSL as a protocol is entirely obsolete, but its name lives on as shorthand for web encryption. Nearly all web traffic is now encrypted using TLS, and SSL certificates have become a fundamental, invisible part of everyday internet use. What began as an experimental solution for protecting credit card numbers has evolved into a global security infrastructure that enables trust, privacy, and safety across the modern web.