Nowadays, a large portion of Web traffic is encrypted using HTTPS. It is becoming increasingly prevalent, especially since the introduction of Let’s Encrypt, a Certificate Authority (CA) supported by major companies in the industry. Let’s Encrypt provides SSL/TLS certificates completely free of charge with 90-day validity.
Generally, certificates are tied to one or more specific domain names, so if you have a certificate for “www.example.com,” you can only use it with this exact domain name. On the other hand, wildcard certificates are issued for a parent domain name and can be used with any subdomain of the parent domain. For instance, a wildcard certificate for *.example.com can be used for “www.example.com,” “account.example.com,” “mail.example.com,” etc. Wildcard certificates, hence, bring the benefit of only having to obtain and renew a single certificate for all your present and future subdomains.
Here’s how to obtain a wildcard certificate for a registered domain name from Let’s Encrypt on Ubuntu, Debian and other Debian-based distributions – see https://www.maketecheasier.com/obtain-free-wildcard-ssl-certificates-lets-encrypt/ where they also cover various well known hosting services.
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