The package ca-certificates consists of trusted root and intermediate certificates that the operating systems and applications use to establish secure connections. While making a connection to an HTTPS website or other TLS-based services, the software can use these certificates to check if the certificate from the remote server is from a trusted certificate issuer. The importance of keeping the certificate database updated lies in the fact that trust can be established and revoked over time. On Linux systems, for instance, the software may depend on the trusted certificate bundle provided by the operating system.