# What Is Certificate Chain? Definition and Examples > Certificate chains are ordered lists of certificates, from a server's leaf through intermediates to a trusted root, each signed by the next. Source: https://ssl.sh/glossary/certificate-chain/ Last updated: 2026-11-10 A certificate chain is the sequence of certificates a client uses to connect a server's leaf certificate to a [root certificate](https://ssl.sh/glossary/root-certificate/) in its [trust store](https://ssl.sh/glossary/trust-store/). Each certificate's issuer name matches the subject of the next one, and each signature verifies with the next certificate's public key. The server sends the leaf plus intermediates; the client supplies the root and builds the path itself. ## Why it matters Path validation checks every link: signatures, validity dates, basic constraints, name constraints, key usage and, where available, revocation status. If an intermediate is missing, expired or out of order, clients report errors such as "unable to get local issuer certificate". Because of [cross-signing](https://ssl.sh/glossary/cross-signing/) a certificate can have more than one valid path, and different clients may pick different ones, which is why the same site can work on a new phone but fail on an old one. ## Example ```bash openssl s_client -connect example.com:443 -servername example.com -showcerts