This directory contains your keys and certificates. `privkey.pem` : the private key for your certificate. `fullchain.pem`: the certificate file used in most server software. `chain.pem` : used for OCSP stapling in Nginx >=1.3.7. `cert.pem` : will break many server configurations, and should not be used without reading further documentation (see link below). We recommend not moving these files. For more information, see the Certbot User Guide at https://certbot.eff.org/docs/using.html#where-are-my-certificates.