The location bar or address bar is that part of the web browser where you can type in a web address to go directly to a site.
This is useful for web users who have received a web address on a business card or other printed material, or have written down a web address, and want to go directly to that site without bothering with a search engine as an intermediary.
The location bar will also tell you what web site you are on, and where in that site you are. This will allow you to look at your web browser and confirm that you are on the site you intended to visit before you enter any information into that site, such as usernames, passwords, or credit card information.