Protocol Identifier is defined as the identifier that points to a specific protocol which will be utilized to search the resource. For example, consider the URL, or Uniform Resource Locator for eHow, "http://www.ehow.com". In this URL, "http" is referred to as the Protocol Identifier.
URL consists of two parts. Protocol Identifier is the first part of a URL, before the colon, and the other part of the URL, after the colon, is known as Resource Name.
Protocol Identifier is used to indicate different protocols that will be used, such as Hypertext Transfer Protocol or HTTP, File Transfer Protocol or FTP, and File.
Protocol Identifier and the Resource Name in the URL, are set apart from each other with a colon and two forward slashes. For example, in "http://www.ehow.com", http, a Protocol Identifier is separated from the resource name by "://".
Protocol Identifiers can be used for network security when implemented as Port Independent Protocol Identification. This implementation enables you to inspect the targeted protocol.