An SSL (Secure Sockets Layer) certificate is a digital credential that enables secure, encrypted communication between a web browser and a server. While the term "SSL" is still widely used, it has been replaced by the more secure TLS (Transport Layer Security) protocol. SSL/TLS certificates authenticate the identity of a website and ensure that any data transmitted between the website and its users is encrypted. Each certificate includes a public and private key, with the public key used to encrypt data while the private key is responsible for decrypting information.

Secure Sockets Layer (SSL) and Transport Layer Security (TLS) both represent cryptographic protocols and both rely on digital certificates to authenticate website identities. While they share a similar purpose, TLS is the more advanced and secure successor to SSL, addressing vulnerabilities in SSL and introducing stronger encryption, improved performance, and enhanced security features. Although SSL has officially been deprecated, the term "SSL" is still commonly used to refer to TLS in many contexts. Today, virtually all secure web connections rely on TLS.

Encryption strength depends on the key length used during the encryption process, with 128-bit and 256-bit encryption being the most common. While both offer strong protection, 256-bit encryption is considered more secure because its longer key length results in an exponentially higher number of possible key combinations, making it more resistant to brute force attacks. That said, 128-bit encryption is still secure and sufficient for some applications. The actual encryption strength used in an SSL/TLS connection is determined by the cipher suite negotiated during the TLS handshake between the browser and the server. BoostSSL certificates meet the highest standards with 256-bit encryption.

An intermediate certificate serves as a bridge between the top-level root certificate and the end-entity certificate, which is ultimately issued to a specific website or organization. Issued by the root CA, the intermediate certificate plays a critical role in establishing a chain of trust that links the highly secure root certificate to the end-entity certificate. As a key part of the trust hierarchy, intermediate certificates ensure that the end-entity certificate is recognized as valid and trusted by web browsers.