There are many plugins in WordPress Plugin Repository that allows you to display Adsense and other ads in your blog but sometimes you like to display add on your header and footer areas, you install a plugin for that then you change your mind to sidebar and inside your post, you install another plugin and when you get tired of checking plugins one by one then you start editing your theme files but now reading this tutorial you can show ads anywhere you want in your blog without using any extra plugin and without editing and theme file.