A domain name is essentially a name for an IP address of a website. Since IP addresses consist of a combination of numbers, domain names are a way for people to remember where a website can be found without having to memorize combinations of numbers and periods.

IP addresses look like this:
173.194.70.113

If you type the above IP address in your browser, you will be redirected to Google. It is way easier to remember Google that the IP Address. It is almost impossible for a person to remember hundreds of IP addresses for all the sites they want to visit every day. A domain name is an easy-to-remember address of a website. Both lead to the same web site.