Google Chrome extensions are programs that can be installed into Chrome in order to change the browser's functionality. This includes adding new features to Chrome or modifying the existing behavior of the program itself to make it more convenient for the user.
How you use a Google Chrome extensions depends on the particular extension. Some extensions work in the background and perform particular tasks automatically. Other extensions will add menu options to the menu when you right-click on a web page. Most extensions will also add small icons to the right of the address field in the browser. These icons can be clicked on or right-clicked to access the functionality of the extension.
While some developers offer direct downloads of their extensions, the best place to install get a Chrome extension is from Google's Chrome Web Store. While this site is called a store and there are some extensions that you need to purchase before you can use them, the vast majority of extensions listed here are for free.
To use the store, simply search for an extension by keyword or browse the categories listed in the store. It is important to be careful when installing extensions, though, as the more extensions you install the more memory Chrome will use on your computer. Therefore, only install an extension that you plan on using.
Furthermore, it is important to read the reviews of an extension before you install it. This is because there are many that do not work properly or are designed to just change your search engine, start page, or new tab page. These types of extensions should be avoided.