SSL certificate DigiCert Secure Site Pro Wildcard

Standard certificates such as Thawte WebServer Certificate, Comodo InstantSSL, Comodo PremiumSSL, VeriSign Secure Site, VeriSign Secure Site Pro.
Besides the domain ownership confirmation you will also need the required organization founding documents while ordering SSL certificates.

If you want to protect your domain in the national language (e. g. 百度.中文网), then you will need to order a certificate with IDN support.

Certificates with subdomains support (Wildcard) such as RapidSSL WildCard, Comodo PositiveSSL WildCard, Comodo PremiumSSL WildCard, Thawte Web Server Wild Card Certificate. SSL Certificate will operate on all subdomains of the main domain name, and you do not need to buy several different certificates. These certificates can be with the verification of either the mere domain or the complete organization incorporation data.

Certificate with high level of Server Gated Cryptography (SGC) - such as Thawte SGC SuperCert orVeriSign Secure Site Pro with EV (SGC).
Those certificates are used if your clients have the old browser versions. Thus the high level of encryption will be used even in the browser support absence.

You can use one certificate for many domains instead of ordering many certificates.