A domain name is the readable web address you type into a browser to visit a website, like wikipedia.org or nasa.gov. Domain names exist because computers actually find websites using long strings of numbers called IP addresses, which are nearly impossible for humans to remember. A domain name acts like a contact name in your phone: instead of memorizing someone's ten-digit number, you just tap their name.

When you type a domain name, specialized computers called DNS servers instantly translate it into the numeric address that leads to the right website, like a phonebook that works in milliseconds. This system makes the internet usable for ordinary people.

Domain names have parts separated by dots. The last part, like .com or .edu, is called the top-level domain and can indicate the type of site: .edu for educational institutions, .gov for government agencies, .org for organizations. The part before that, like wikipedia in wikipedia.org, is the actual name someone chose and registered.

People and companies must register domain names through special companies, and once registered, that exact name belongs to them alone for as long as they keep renewing it. If someone has already registered coolrobots.com, you'll need to choose a different name. Some memorable domain names are worth millions of dollars because they're easy to remember and attract visitors.