As the name suggests, extensions are packages meant for extending features of a Joomla web site. There are many extensions available on the Internet, ranging from large complex components to small lightweight modules and plug-ins. You can add features such as a chatting functionality, discussion forum, and shopping cart to your web site by installing the respective extension.
As described in the following list, all types of extensions can be installed or uninstalled with the help of the Extension Manager:
- Components: A component is an independent application with its own functionality, database, and Installing a component in your web site is just like adding an application to your web site. For example, forums, shopping carts, newsletters, and guest books are all examples of components. A component can consist of one or more modules.
- Modules: Modules add functions (features) to an existing component (application) of your web site—for example, a login module, a sign-in module of a guest book component, a subscription module of a newsletter component, or a digital counter module of a guest book A module is one running unit of an application and cannot be a stand-alone component.
- Plug-ins: Plug-ins were called mambots in Joomla 1.0.x, but have been called plug- ins since Joomla 1.5.x. A plug-in is a function that can be applied to a particular component or an entire web site—for example, a search plug-in that can be used by visitors to search the forum or a bookmark plug-in to place bookmarks on desired contents of the web site.
■ Note To understand the differences among components, modules, and plug-ins, consider this example: the shopping cart is a component that has several modules, including modules for maintaining inventory, storing payment information, and printing bills. Plug-ins can be added to the shopping cart component, including a plug-in to change the price of a particular product or a search plug-in to enable searching for a desired product from the shopping cart. You can also use external companies that can install any Joomla extension for you.
- Languages: This type of extension provides a facility for presenting the front end and back end of Joomla in any desired language. That is, you can present your Joomla web site in different languages without much effort.
- Templates: The purpose of a template is to give a dynamic appearance to your web site. A template contains the style sheets, locations, and layout of the web contents being displayed. It separates the appearance of the web site from its content.
Let’s open the Extension Manager by selecting Extensions ➤ Extension Manager. You’ll see a screen like the one shown in Figure 9-1.
The Install tab enables you to install all types of extensions. The remaining tabs are for updating and managing the respective extensions.
Note In Joomla, you can install an extension from any location on the Internet by providing the URL of the extension’s installation That is, you can install an extension without downloading it to your local disk drive.
Source: Harwani B M (2015), Foundations of Joomla!, Apress; 2nd ed edition