When your blog grows your categories expands. This tutorial is about a plugin that allows you to display top level categories and present sub categories, they expands and show their sub categories when you click them and all this happens in beautiful jQuery Animation.
Folding Category List (FoCaL) is a free WordPress plugin that allows you to show only top level categories and the current sub-categories. This way your website saves a lot of screen space on your sidebars etc and even you can animate the menu as either a drop down horizontal menu or using an accordion style vertical menu with cool jQuery animations. More features about this plugin are listed on its page or you can check it like working here.
Installation & Usage: Install and activate this plugin then visit your Dashboard -> Settings -> FoCal and make customizations as per your taste. The plugin options allows you to set Some Cache Options, Individual Widget Settings, Category Expansion, Priority, Order, Count, CSS, Animation, Links and even SEO options.
Now your second step is to visit your Dashboard -> Appearance -> Widgets page and drag its widget to your sidebar or any other widget area of your theme. The widget allows you to select from settings definitions you created from its options page, you may leave it to use default definition.