Secure Socket Layer

Transport Layer Security (TLS), preceded by SSL, are cryptographic protocols, that provide communication security.

client-server applications use TLS protocols
aims to provide data integrity between two communicating computer applications
standard for establishing an encrypted link between a web server and a browser
link ensures all data transfer is private
an SSL connection requires an SSL certificate, using public and private keys
public key is placed into Certificate Signing Request (a CSR file containing your details)
- submit the CSR, then during SSL certificate application process, the certification authority will validate your details, and issues an SSL certificate containing your details and allowing you to use SSL.
SSL certs contain the domain name, company name, your address, your city, country
SSL cert matches to the private key, held on the web server

Sockets are endpoints of two way communication. Unix domain sockets use TCP or UDP. SSL (secure socket layer) is the standard security protocol.

Certbot is an automatic client that fetches and deploys SSL/TLS certs for webservers. Client for Let's Encrypt

wget https://dl.eff.org/certbot-auto
chmod a+x certbot-auto
./certbot-auto
# kill server
./certbot-auto certonly