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). WARNING: DO NOT MOVE OR RENAME THESE FILES! Certbot expects these files to remain in this location in order to function properly! We recommend not moving these files. For more information, see the Certbot User Guide at