SSL root certificate (SSL root certificate) is a digital certificate in the public key infrastructure (PKI) system, which is used to verify the security of SSL/TLS connections. It is the basis of the entire SSL certificate system and is used to establish a chain of trust to ensure secure communication with the server.

A root certificate is a top-level certificate issued by a trusted certificate authority (CA). It serves as the root node of the chain of trust and is used to verify the validity of other certificates. Root certificates are highly trusted and secure certificates, and their public keys are pre-installed in various operating systems, browsers and devices. When a user visits a website protected by SSL/TLS, the system will automatically verify the validity of the server certificate, including verifying whether the server certificate is issued by a trusted root certificate.

The role of the root certificate includes the following aspects:

1. Verify the identity of the server: When the client (such as a web browser) establishes a secure connection with the server, the server will provide the client with an SSL certificate. The client uses the root certificate to verify the validity and authenticity of the server certificate to ensure the security of the connection.

2. Encrypted communication: The root certificate is used to encrypt the communication between the client and the server. It provides encryption algorithms and keys to ensure confidentiality and integrity during data transmission.

3. Establish a chain of trust: the root certificate is used to build a chain of trust and verify the credibility of the server certificate. The client checks that the server certificate is signed by a trusted authority to determine if the connection is secure.

4. Prevent man-in-the-middle attacks: By verifying the validity of the server certificate chain, including the root certificate, it is possible to prevent man-in-the-middle attacks. A man-in-the-middle attack is an attack in which hackers try to insert themselves as a man-in-the-middle on a server and steal sensitive information.

In short, the role of the SSL root certificate is to ensure the establishment of a secure connection, verify the authenticity of the server, and encrypt the transmitted data to provide a safe and credible communication environment. It is essential to protect users' privacy and data security.