SSL
SSL (Secure Sockets Layer) is the common name for the security protocol that encrypts communication between a web browser and a server. It has been superseded by its successor standard, TLS, though the name SSL persists in everyday usage in phrases such as "SSL certificate."
- SSL is the common name for a security protocol that encrypts web traffic to prevent eavesdropping and tampering.
- Every version of the original SSL protocol has been retired; the standard actually in use today is its successor, TLS. The name lives on by convention, as in "SSL certificate."
- HTTPS means "HTTP protected by SSL/TLS," with SSL/TLS providing the encryption layer and certificate handling underneath.
- Google officially announced in 2014 that it uses HTTPS as a ranking signal, and today treats it as part of page experience.
- Free certificate authorities such as Let's Encrypt make it possible to issue and renew SSL/TLS certificates automatically at no cost.
What SSL Is
SSL (Secure Sockets Layer) is a security protocol that encrypts the data exchanged between a web browser and a server, guarding against eavesdropping, tampering, and impersonation by third parties. It keeps the passwords, payment details, and personal information a user enters from traveling across the network in plain text. Today, common expressions like "SSL certificate" and "enabling SSL" have effectively become idioms that actually refer to the successor standard, TLS.
Relationship Between SSL and TLS
SSL is the original protocol that emerged in the 1990s, and because of known security vulnerabilities, every version of SSL is now deprecated. In 1999, TLS (Transport Layer Security) 1.0 was published as the successor to SSL 3.0, and subsequent versions TLS 1.2 and 1.3 brought stronger cipher algorithms (such as AES), improved authentication, and more robust key-exchange mechanisms. In other words, nearly everything we call "SSL" today actually runs on TLS.
| Aspect | SSL | TLS |
|---|---|---|
| Standard status | Original protocol, all versions deprecated | Successor to SSL, current standard (1.2 / 1.3) |
| Introduced | Mid-1990s | 1999 (TLS 1.0) onward |
| Cipher algorithms | Older, with known vulnerabilities | Modern (AES and others), vulnerabilities addressed |
| Practical use | No longer used in production | Used on every real HTTPS connection |
| The term "SSL certificate" | Called SSL by convention, but in practice a TLS certificate | |
SSL Certificates and HTTPS
An SSL/TLS certificate is a digital proof of identity issued by a certificate authority (CA). It verifies domain ownership, lets the browser trust the server's identity, and serves as the foundation for the encrypted key exchange. HTTPS is HTTP running on top of this SSL/TLS security layer—that is, "HTTP protected by SSL/TLS." Put another way, SSL/TLS is the technology that encrypts the data and provides the certificate, while HTTPS is the protocol that uses that encryption to communicate securely. The padlock icon in the browser's address bar indicates that an HTTPS connection has been established with a valid certificate.
Let's Encrypt is a free, automated, and open certificate authority operated by the nonprofit ISRG. It automates the issuance, renewal, and revocation of certificates through the ACME protocol (RFC 8555). Because anyone can apply an SSL/TLS certificate at no cost, it has greatly expanded the adoption of HTTPS across the web.
SEO Implications
In August 2014, Google announced on its official blog that it had begun using HTTPS as a ranking signal. At the time, Google noted that this was a very lightweight signal—affecting fewer than 1% of all search queries—and carried less weight than other signals such as high-quality content. It also said it might strengthen the signal over time to encourage every website to migrate from HTTP to HTTPS. Today, Google treats HTTPS not as a standalone ranking factor but as a component of page experience, which its core ranking systems evaluate holistically.
From an SEO standpoint, applying SSL/TLS goes beyond a simple ranking boost—it is a prerequisite for trust and a good user experience. Without HTTPS, browsers display a "Not Secure" warning that raises bounce rates and undermines confidence on transactional pages such as checkout and login.
Implementation Checklist
- Apply an SSL/TLS certificate across the entire site so that every page is served over HTTPS.
- 301-redirect HTTP requests to HTTPS to avoid duplicate and mixed content.
- Standardize canonical tags and sitemap URLs on the HTTPS versions.
- Check that a noindex robots meta tag is not blocking indexing (per Google's recommendation).
- Set up automatic renewal before certificates expire (for example, Let's Encrypt with an ACME client).
- Disable legacy SSL and outdated TLS, and require TLS 1.2 or higher.