You are viewing a list of pages and/or additional subcategories under the category called Platform. For more quick information on the Joomla! Platform see:

Information icon You can browse the Joomla! Documentation Wiki either from this page or by using the Category Tree Page.
Please note, if a page is not given a category, then it will not be listed here.
Additional information next to each category listed is as follows. (# C(ategories), # P(ages), # F(iles))