Let's Encrypt: out of beta, free certificates for everyone
source: letsencrypt.org
Why it is worth attention: Let's Encrypt left beta in April 2016 and offered domain-validated TLS certificates for free, fully automated through the ACME protocol. The barrier between http and https dropped from cost and manual administration down to one client command.
What to take from it: automated certificate renewal (typically a cron job or a systemd timer running an ACME client) belongs to basic server hygiene just as much as regular package updates – a certificate nobody watches eventually expires.