Encryption and trust.
SSL AND TLS
Protocols encrypting traffic between a visitor and a server.
TLS is the current form; SSL is still used as the common term.
HTTPS
A page served over an encrypted connection.
CERTIFICATE
The file proving a site's identity, enabling HTTPS.
AUTOSSL
The cPanel feature obtaining and renewing certificates automatically.
MIXED CONTENT
A secure page loading an insecure resource, which breaks the padlock.
CERTIFICATE AUTHORITY
The organisation issuing certificates.
SELF-SIGNED CERTIFICATE
One issued by the server itself, which browsers do not trust.
WILDCARD CERTIFICATE
One covering a domain and all its subdomains.
HSTS
A setting instructing browsers to use HTTPS only.
TWO-FACTOR AUTHENTICATION
A second verification step beyond a password.
FIREWALL
A system filtering traffic before it reaches the server or application.