An IP address also known as an A record in DNS, is the address the internet uses to figure out where things like your website, and email go.
Below is an example of what it might look like:
With an IP address you can locate the computer(server) your webiste is on and point your domain name to it so others don’t have to type that long number address, that all in all is not all that human friendly to start with!
When people type in whateveryourdomainis.com your web browser(Internet Explorer, FireFox, Google Chrome) looks at the IP address and goes to that server to find your website and bring it up on the screen. Same thing happens when you type in firstname.lastname@example.org in your email program(Outlook, Mac Mail, etc.),
To sum it up knowing what your IP address is can be a big time saver when buying that new domain you always wanted for your new site!