Products differ in how many names one certificate can protect. On MixSSL, each product page and the catalog filters show whether wildcards and additional names are supported and how many extra names are included or can be purchased.
Single domain
Covers one hostname such as www.example.com. Good for a simple company site. Choose a standard DV or OV product without wildcard or multi-domain features.
Wildcard
Covers one domain and all its subdomains at one level, for example *.example.com (shop.example.com, mail.example.com). Wildcards do not cover the bare domain example.com unless you also list it in the certificate.
In the catalog, enable the Wildcard filter to list wildcard-capable products only.
Multi-domain / SAN
One certificate lists several different hostnames (for example example.com, example.net, and shop.example.com). Useful if you run more than one brand or domain on the same server.
Choose what you actually use
Pick the product that matches how many sites and subdomains you run, so you do not pay for capacity you do not need. When ordering, the CSR and verification step must include every hostname you need.
Getting help
Not sure whether you need a wildcard or SAN certificate? Use the contact form on the MixSSL website.