# What Is SSL (Secure Sockets Layer)? Definition and Examples

> SSL (Secure Sockets Layer) is the original Netscape protocol for securing network connections; TLS replaced it, but the name lives on informally.

Source: https://ssl.sh/glossary/ssl/
Last updated: 2026-11-10

SSL is the protocol family Netscape created in the mid-1990s to encrypt and authenticate traffic between browsers and web servers. SSL 1.0 was never released publicly, SSL 2.0 shipped in 1995 and SSL 3.0 in 1996; the IETF then standardised the design as [TLS](https://ssl.sh/glossary/tls/) 1.0 in 1999. Every SSL version is now broken and prohibited, yet "SSL" survives as everyday shorthand for TLS, [certificates](https://ssl.sh/glossary/ssl-certificate/) and HTTPS in general.

## Why it matters
When someone asks for an "SSL certificate" or an "SSL checker", they almost always mean TLS. The distinction still matters in configuration: a server that accepts SSL 3.0 is exposed to [POODLE](https://ssl.sh/glossary/poodle/), and RFC 7568 formally deprecated SSL 3.0 in 2015. Modern servers should offer only TLS 1.2 and TLS 1.3. Library names such as OpenSSL and BoringSSL, and directives such as nginx's `ssl_protocols`, keep the old name purely for historical reasons.

## Example
In nginx the directive is still called `ssl_protocols`, but the values you list should be TLS versions only:

```nginx
ssl_protocols TLSv1.2 TLSv1.3;
```

## Common misconceptions
- **SSL and TLS are competing products you must choose between.** They are successive versions of one protocol line; anything sold or configured as "SSL" today actually runs TLS.
- **An SSL certificate only works with the SSL protocol.** Certificates are protocol-independent X.509 documents; the same certificate is used with TLS 1.2 and TLS 1.3.
- **Turning off SSL 3.0 will lock out normal visitors.** Mainstream browsers stopped using SSL 3.0 after POODLE was published in 2014, so disabling it has no effect on real users.

## Related terms

- [TLS](https://ssl.sh/zh/glossary/tls/): TLS 是 IETF 制定的传输层安全协议，为 HTTPS 等网络连接提供加密、完整性保护和服务器身份认证，是 SSL 的继任者。
- [SSL 3.0](https://ssl.sh/zh/glossary/ssl-3-0/): SSL 3.0 是 Netscape 设计的安全套接层协议的最后一个版本，1996 年发布，2014 年被 POODLE 攻破，2015 年被 RFC 7568 废弃。
- [HTTPS](https://ssl.sh/zh/glossary/https/): HTTPS 是在 TLS 加密连接之上传输的 HTTP，默认使用 443 端口，使网页内容、Cookie 和表单数据被加密，并验证服务器身份。
- [SSL 证书](https://ssl.sh/zh/glossary/ssl-certificate/): SSL 证书是由 CA 签名的 X.509 证书，把公钥与一个或多个域名（或 IP 地址）绑定，供 TLS 客户端验证服务器身份。
- [POODLE](https://ssl.sh/zh/glossary/poodle/): POODLE 是 2014 年公布的攻击（CVE-2014-3566），利用 SSL 3.0 不校验 CBC 填充的缺陷，从加密连接中逐字节还原 Cookie 等秘密。
- [TLS 握手](https://ssl.sh/zh/glossary/tls-handshake/): TLS 握手是 TLS 连接开始时的一组消息交换，客户端与服务器在其中协商协议版本和密码套件、验证服务器身份并派生会话密钥。