We usually browse websites using the names which can also be domain names, but the computer cannot work with domain names . It does not fetch data based on these domain names.
When ever the user searches for a website using domain name, computer has to communicate with the other servers to fetch the content. The browser makes a request to the respective URL. It will be mapped to the remote address of that webpage.
This mapping is done by Domain Name System(DNS). It resolves the domain names into IP addresses. This works with DNS resolver. It is the hard code IP address used by our system.
DNS resolver used by computer is usually choose by your ISP(Internet Service Provider). However, this could be configured to a different resolver in your OS's network settings. DNS resolver might not directly know the IP address of the domain name we requested. It reaches out to several other DNS resolvers which might know the IP address of Domain name.
The searching is done by firstly knowing where the addresses of the specific extensions are stored. Say suppose .com addresses are stored with the respective resolver. This resolver could also be referred as server.
Then based on the extension the IP address of specific domain name is searched. Finally when the system's resolver gets the targeted domain's IP address it returns to the browser.
After obtaining the address computer might cache the address of it so that it can directly obtain the next time it wants to visit.