Certbot (previously, the Let's Encrypt client) is a client that
fetches and deploys SSL/TLS certificates for webservers.
Certbot was developed by EFF and others as a client for Let's Encrypt
and was previously known as “the official Let's Encrypt client” or
“the Let's Encrypt Python client”. Certbot will also work with any
other CAs that support the ACME protocol.
Certbot can automatically configure a webserver to start serving
over HTTPS immediately. For Apache, it can also optionally automate
security tasks such as tuning ciphersuites and enabling important
security features such as HTTP-to-HTTPS redirects, OCSP stapling,
HSTS, and upgrade-insecure-requests.