Let’s Encrypt

ACME (Automatic Certificate Management Environment) is an open source protocol that automates the process of obtaining and renewing SSL/TLS certificates.

Let’s Encrypt (LE) created this protocol and uses it to issue certificates.

Certbot is a popular ACME client that communicates with the LE servers to

  • validate domain ownership
  • request certificates
  • install the certificates on the web server
  • handle automatic renewals

Let’s Encrypt was founded by the Internet Security Research Group. Certbot was created independently by the EFF and is maintained by them.

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