DNS stands for Domain Name System. It's a system that maps human-readable domain names (like www.example.com) to IP addresses (like 192.0.2.1). DNS is what allows us to use easy-to-remember domain names instead of having to remember IP addresses.
When you type a domain name into your browser, your computer will first look in its local DNS cache to see if it already has the IP address for that domain name stored. If it does, it will use that IP address and skip the rest of the steps.
If the IP address isn't in the local DNS cache, your computer will then send a request to a DNS server (usually provided by your ISP) to resolve the domain name into an IP address. The DNS server will then look up the IP address in its own cache and return it to your computer if it finds it.
If the DNS server doesn't have the IP address in its cache, it will start querying other DNS servers until it finds the correct IP address or decides that the domain name doesn't exist.
Once your computer has the IP address, it will connect to that IP address and load the website.
DNS works by using a system of hierarchical name servers. There is a root name server at the top of the hierarchy, and then there are various levels of subdomains below that. For example, ".com" is a subdomain of the root domain, and "google" is a subdomain of ".com". When you type in a domain name, your computer starts at the root name server and then queries each level of the hierarchy until it finds the correct IP address for the domain name you entered.
DNS is important because it makes the internet more user-friendly by allowing us to use domain names instead of IP addresses. It also makes sure that we are able to connect to the correct website even if the website's IP address changes.
Human-readable domain names are mapped to IP addresses so that we don't have to remember difficult strings of numbers when we want to visit our favorite websites.