As indicated earlier features in SharePoint enable you to toggle functionality On or Off. All features created using farm solutions are deployed to a corresponding folder in the <14 Hive>\Template\FEATURES directory. You find a feature.xml file within this directory. Features created using sandboxed solutions get deployed to the database.
You already created a couple of features in this hour in a farm solution and in a sandboxed solution. To see these features activated, go to Site Actions, Site Settings, Site Collection Features under the Site Collection Administration section (see Figure 3.16).