A template controls the graphical presentation of your website. It determines the layout, colors, type-faces, graphics and other aspects of design that make your site unique. There are two types of templates: “Site template” for front-end presentation and “Administrator template” for back-end presentation.
To view your templates....Go to “Extensions” => “Template Manager”. The window below will appear.
The site templates change the way your website looks to visitors.
Most of the time, you will be dealing with the site templates to change public look-n-feel of your website. Below is an example of a Site template, it is Joomla's default blog template.
Administrator templates changes the way the administrator interface looks.
If you are building a website for yourself, then you will probably never need to change your back-end template. When building websites for clients, you might need to slightly customize the administrator template to reflect your customer’s brand. Below is a screen shot of an Administrator template.
The quickest and easiest way to enhance the design of your website is to use an existing Joomla template. There are many available on the Internet.