Domain registration and DNS are the two services behind every web address. Domain registration is buying a web address, such as a business's own .in name, for a yearly fee. DNS, the Domain Name System, is the lookup that turns that name into the numeric address of the server where the website lives.
A company called a registrar sells the name. It records the owner in a central list, called the registry, and the owner pays every year to keep the name. For names ending in .in, the registry is run by NIXI, the National Internet Exchange of India, and registrars sell the names to the public. Some registrars also sell through resellers, smaller companies that sell the names under their own brand.
Say a tailoring business in Surat wants a website. The owner searches a registrar's website for a name. A suitable .in name is free, and she pays about ₹700 for the first year. The renewal each year costs a little more. The registrar records her as the owner, with her email address and phone number.
The name is not useful yet. A browser cannot reach a server with a name alone. It needs the server's IP address, a number such as 198.51.100.24 that identifies one computer on the internet. This is the job of DNS. In the registrar's DNS settings, the owner adds a few records. An A record says: this name belongs to the server at 198.51.100.24, which is her web hosting server. An MX record says which server receives the business's email.
Now a customer in Vadodara types the name into her phone. The phone asks a DNS resolver for the address. A resolver is a server, usually run by the customer's internet provider, that finds addresses for its users. The resolver asks the servers that hold the list of .in names, and they point it to the registrar's DNS servers. These reply with 198.51.100.24. The phone connects to that address, and the page loads. All of this takes a fraction of a second. The resolver then remembers the answer for a set time, so that the next customer's lookup is faster.
Most registrars also sell an SSL certificate. The certificate proves that the website really belongs to this business, and it lets the browser encrypt everything sent to the site. The browser shows it as a padlock next to the web address. The registrar obtains the certificate from a certificate authority. The page on public key infrastructure explains why browsers trust it.
What can go wrong? If the owner forgets to renew, the website and the email stop working. After a short grace period, anyone can buy the name. Attackers also target DNS itself. For example, they may change a record so that customers reach a fake site. DNS security products protect against this.
Larger sites often move their DNS to a content delivery network. Its DNS servers answer from many cities, and send each visitor to the nearest copy of the site.