Certificate Authority or Certification Authority, CA, is an entity that issues digital certificates for use by other parties such as website designers. Website designers obtain this certificate of authority for the website that they are designing. The Certificate Authority issues website designers a digital certificate which is also known as an identity certificate or a public key certificate, which uses a digital signature to identify the owner of the certificate or web site as who they say they are.
Website designers place this hidden public key to the certificate of authority on the web site so users can accept it or not. A certificate authority (CA) is an authority in a network that issues and manages security credentials and public keys for message encryption as done by website designers. Before issuing website designers a certificate the Certificate Authority will check with a registration authority to verify information provided by the requestor of a digital certificate.
If the registration authority verifies the requestor's information, the Certificate Authority can then issue the website designers or other requestor a certificate. The website designers will place this certificate which contains the owner's public key, the expiration date of the certificate, the owner's name, and other information about the public key owner, in the web site for access by the web site user. Certificate Authority are a critical component in data security and electronic commerece because they guarantee that the two parties exchanging information are really who they claim to be. This is why website designers are so familiar with the Certificate Authority.
When you need to run a website (https), mail (ssl/tls) or similar over an encrypted link, you need an SSL certificate, which is generally obtained and installed by website designers. There are two basic types of certificates used by website designers. The first type used by website designers is a certificate signed by a Certificate Authority (CA). This certificate will work out of the box for your users.
All Certificate Authority certificates that are recognized by browsers by default are commercial and costs money, generally $150.00 every year or two. These also have to be renewed yearly or bi-yearly. There other basic certificate is one that website designers generate themselves and are self-signed. These are free and require a user's approval. Because of the warning that pops up for the user when the website is requested, they can be scary for the un-experienced user.
A commercial certificate is signed by a certificate authority (CA). By signing this they are saying that they believe that you are who you say you are. The browser/application has a list of trusted CA certificates and can check; when the connection is made it will check the signature against this list of trusted CA. A self-signed certificate (one that you generate) will need to be installed in all browsers/applications you are going to use it with or the users will have to approve the certificate each time they visit the site. In addition, when it fails due for renewal, you will have to re-install the certificate on all locations.