Unique Identifier

Unique identifiers or UID’s are numbers and letters that allow the identification of objects within a computer system. They indicate where an object is located and how it can be reached. Unique identifiers allow the control and interaction of different objects or abstract datasets within a computer network. If a data packet is to be sent from one computer to another, a unique identifier represents the exact address of the sender and receiver.

General information[edit]

UIDs consist of a number and/or character sequence in hexadecimal notation up to 128 bits. They are generated by means of a schema, depending on the system used. The abbreviation mailto: mustermann@muster.de is a unique identifier, which enables the direct sending of emails to Websites. mailto would be the schema used here.

Likewise, FTP addresses are UIDs, whereby the FTP protocol is the schema. In computer networks, objects are controlled by means of unique identifiers which, as MAC addresses, enable the interaction of a particular network adapter with the network (e.g. Internet or home network). The MAC address specifies the location and type of the connection. The HTTP protocol is the schema in this case.[1]

The concept of unique identifiers is based on Microsoft’s GUIDs (Global Unique Identifier), which has been used by Microsoft programs since the late nineties. Nowadays, a random or named-based schema is usually generated since unique identifiers that issue a time stamp have the disadvantage that both the generating object (e.g., a PC) and the time of access are disclosed.

According to critics, if the originator of a unique identifier is apparent, privacy will not be guaranteed. Therefore, the schemata and Algorithms have been improved to create unique identifiers to ensure privacy protection by using random algorithms or namespaces. The schemata can also be combined according to the syntax of unique identifiers.

Practical relevance[edit]

Unique identifiers are used in different areas. Typical examples are computer networks, but they are also utilized in the banking sector (BIC) and trade (serial numbers of products.[2]

URIs and URLs are particularly worth mentioning with regard to network architectures. A Uniform Resource Identifier (URI) specifies the address of content pages on the World Wide Web, such as text, video, or audio sources. However, a URL (Uniform Resource Locator) is considered the best-known case of a URI, where a particular location is identified, which is not possible with all URIs. By definition, a URL is a subset of URIs and URI is a concept also applied in other areas. URLs are only used to resolve addresses in the World Wide Web, but are the most common usage type of URIs.

Relevance to search engine optimization[edit]

Unique identifiers and, in particular, URL's are an important topic in search engine optimization. URLs are directly readable and resolve IP addresses into text characters. They should not only be concise, but also include the most important keywords. They should use keywords to describe the content of the website so that user and search engines know what the website is all about.

The following criteria must be followed for URLs:

  • Hyphens separate the individual words.
  • Other characters such as colons and spaces should not be used.
  • The entire URL should not be larger than 2048 characters because it is otherwise unreadable for Internet Explorer. [3]

When creating Dynamic Websites, it is also necessary to use Parameters such as Session ID sparingly and place them at the end of a speaking URL. Optionally, such URLs can be rewritten using mod-Rewrite in the htaccess file to turn dynamically generated URLs into static URLs. Search engine-conform URLs can influence the Ranking of a website. This, however, must be accompanied by a good URL structure and other OnPage actions.


  1. A Universally Unique IDentifier (UUID) URN Namespace. Internet Engineering Task Force. Accessed on 12/01/2013
  2. Unique Identifier. Whatis.com. Accessed on 12/01/2013
  3. URL. Moz.com. Accessed on 12/01/2013

Web Links[edit]