There are several different types of SSL certificates. One certificate can apply to a single website or several websites, depending on the type:
- Single-domain: A single-domain SSL certificate applies to only one domain (a “domain” is the name of a website, like www.cloudflare.com).
- Wildcard: Like a single-domain certificate, a wildcard SSL certificate applies to only one domain. However, it also includes that domain’s subdomains. For example, a wildcard certificate could cover www.cloudflare.com, blog.cloudflare.com, and developers.cloudflare.com, while a single-domain certificate could only cover the first.
- Multi-domain: As the name indicates, multi-domain SSL certificates can apply to multiple unrelated domains.
SSL certificates also come with different validation levels. A validation level is like a background check, and the level changes depending on the thoroughness of the check.
- Domain Validation: This is the least-stringent level of validation, and the cheapest. All a business has to do is prove they control the domain.
- Organization Validation: This is a more hands-on process: The CA directly contacts the person or business requesting the certificate. These certificates are more trustworthy for users.
- Extended Validation: This requires a full background check of an organization before the SSL certificate can be issued.