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An ordered list of certificates that starts with an end-entity certificate, includes one or more certificate authority (CA) certificates, and ends with the end-entity certificate’s root CA certificate, where each certificate in the chain is the certificate of the CA that issued the previous certificate. By checking to see if each certificate in the chain was issued by a trusted CA, the receiver of an end-user certificate can determine whether or not it should trust the end-entity certificate by verifying the signatures in the chain of certificates.
NIST SP 1800-16B
NIST SP 1800-16C
NIST SP 1800-16D