What does mean in computer science?



par

This has effectively nothing to do with computer science in general.

It’s just the structure of an Extensible Markup Language (XML) closing tag.
XML is a format based on tags, and HTML, for displaying web pages, is a derivative of XML.


Tags are used to delimit a piece of information and giving it the meaning you want, or in HTML, the meaning the tag is meant for (there are a limited number of predetermined tags - but you can create ones, without entering in the details).

An HTML example:

  1.  

  2. "P" is for "Paragraph" 
  3.  
  4.  
    •  
  7. "UL" is for "Unordered List" 
  9. while "LI" is for "List Item"  
  11. So this is how we represent a simple bullet-points list
  12.  
  13.  
  14.  

  15.  

  16. In HTML you also have "void elements/tags" that don't have closing delimiter, because they have no content. 
  17.  
  18. Here is a blank line insertion in HTML5:  
  19.  
  20. Or in previous HTML versions: 
  21.  
  22.  
  23. An image:
     
  24. cat.gif  
  25.  

That’s why you can sometimes see people writing things like :

  1. HTML is great! No, that's degenerate XML. 

When they’re afraid their sense of irony isn’t understood.

Also, the symbol > alone doesn’t mean anything and isn’t valid HTML, but is often used as a “logo” for HTML. Like on a button that gives you HTML code for integrating a video in your website or blog, for example.