In the technology world it has become more necessary than ever to be able to verify the identity of anyone who is attempting to access a secured web site or database as the incidences of theft continue to rise. The PKI certificate was developed as a result of this need and can be used to quickly verify the identity of the person attempting to access the secured location in question.
The PKI mechanism can be set up to allow open access to a public key such that for example, everyone within a corporate entity can log into the system mainframe using a common user name, but only those who have an authorized and recognized digital signature will be able to access the restricted areas within the network. With this type of security, you can establish a number of access levels based on a need to know basis and protect your sensitive files from those who have no need to see them.