RapidSSL is a 128/256-bit SSL certificate, "single root". The owner of the issuing root is Geotrust . RapidSSL is compatible with 99% of browsers.
Validation is done at the domain level. Delivery of the certificate is generally done within minutes of the confirmation of payment.
Why do I need a SSL certificate?
Security: The purpose of an SSL certificate is to encrypt the connection between the user (browser) and the server so that the informations transferred between the browser and the server can not be intercepted.
Identification: A second purpose is to identify the domain or organization that supports a particular domain so that the user accessing the site is sure it has not been diverted to an unwanted site (another web domain), possibly with negative intent. Browsers automatically check if the certificates are signed by a recognized certification authority.
SEO Ranking: Starting in 2014, Google announced that websites using SSL certificates will have a ranking advantage. While Link Building or On-Page Optimization campaigns require implementation time, obtaining an SSL certificate is easy and fast.