WhyUsingCategories
Overview
Adding a string "CategorySomething" as the very last line to one of your pages is like adding a keyword to your page. But there is some magic in place: That keyword is, according to the "WikiSyntax", linked automatically to a page of that name. If you follow the link, this page, if it does already exist, will create then a list of all pages containing that keyword in the last line. Because it is created dynamically when called, it is definitely up-to-date.
If category names are chosen carefully the concept is even more powerful. Imagine that you have several categories used to distinguish between general articles and articles specific to a particular dialect of APL. An article about a special feature of Dyalog APL "Object Orientation" therefore should get member of the CategoryArticlesDyalogObjectOrientation.
If you search for...
CategoryArticles you get list of all articles, including CategoryArticlesDyalogObjectOrientation
CategoryArticlesDyalog you get a list of all articles related to Dyalog
CategoryArticlesDyalogObj you get a list of all articles relateted to Dyalog starting with "Obj"
Remember, all of these lists are created automatically and dynamically and are therefore are always up-to-date. In case the page(s) are renamed or moved elsewhere, nothing else then the page itself needs to be changed.
Inventing a new category page is simple: choose the appropriate template - the name is obvious. That's it!
You can add several categories to a particular page. For example, you can add both "CategoryDyalogDotNet" and "CategoryGeneralUtils" to a particular page.
When you think about a new category, of course it is a good idea to check the list of already defined categories carefully.
If you feel uncertain what to do it is probably better to do nothing then to add a category just for fun. Admins will take care anyway.