An SSL certificate is what is required to allow you to use a secure HTTPS address in browsers when someone visits your website. An HTTPS address only used to be necessary when confidential information was being transferred such as passwords or credit card data. These days, the major browser and search engine providers are pushing an HTTPS-enabled website as a requirement for everyone by down-ranking insecure websites in their listings and marking them as dangerous in browsers.
Standard or Wildcard
Memset offers two types of SSL certificate. They are both equally secure but work in slightly different ways.
A standard SSL certificate will only work for a single address. This means that if you order a standard certificate for e.g. store.example.com, it will only work for that exact address.
A wildcard SSL certificate will work for any subdomain of a domain name. If you order the certificate for e.g. *.example.com, it will work for https://store.example.com, https://www.example.com, https://mail.example.com and so on.
This means that if you only want to secure a single address then you should get a standard SSL certificate but if you want to secure more than one address for that domain then a wildcard SSL certificate is a better fit.