Let’s Encrypt - Definition from the Hotspot Shield Glossary
Let’s Encrypt is an open CA (Certificate Authority) that was created for use by the public and was developed by the ISRG (Internet Security Research Group). The process is automated and allows users to obtain digital certificates in order to use HTTPS (or SSL/TLS) for websites.
Benefits of Let’s Encrypt include its automatic software which reduces administration time, the security features included, the high level of transparency to ensure any revoked certificates are known, and the fact that it is free to implement on web servers. The main aim of Let’s Encrypt is to allow certification creation without the need for human intervention.