Typing an address and pressing Enter sets off a chain of steps that usually finishes in well under a second: the browser reads the address, finds the server's IP address through DNS, opens a secure connection, asks for the page, and turns the HTML, CSS and JavaScript it gets back into pixels on your screen. Knowing the chain helps you understand where a problem sits when a website doesn't load, and what makes one site faster than another. This guide walks through each step in plain terms.
When you open a web address, the browser parses the URL, looks up the domain's IP address through DNS (checking its caches first), connects to the server over TCP or QUIC, secures the connection with TLS, and sends an HTTP request. The server replies with a status code and the page. The browser then builds the DOM and CSSOM, runs JavaScript, works out the layout and paints the result. A fault at any step, DNS, SSL, server or code, shows up as a different kind of error.
1. The journey in one view
- Parse the address.The browser splits the URL into its parts and decides whether you typed an address or a search.
- Find the IP address.DNS turns the domain name into the server's IP address, using a cached answer if one is fresh.
- Connect.The browser opens a connection to the server, usually on port 443.
- Secure the connection.TLS checks the site's certificate and sets up encryption.
- Request and response.The browser sends an HTTP request; the server returns a status code, headers and the page.
- Render.The browser builds the page from HTML, CSS and JavaScript and draws it.
2. The parts of a URL
Take https://shop.example.in:443/products/shoes?colour=black#reviews:
| Part | Example | What it does |
|---|---|---|
| Scheme | https | How to talk to the server. Modern sites use HTTPS |
| Host | shop.example.in | The name DNS will look up |
| Port | 443 | Usually hidden: 443 for HTTPS, 80 for HTTP |
| Path | /products/shoes | Which page or file on the site |
| Query string | ?colour=black | Extra data for the server, such as filters or search terms |
| Fragment | #reviews | A spot on the page. It stays in the browser and is never sent to the server |
3. How domain names are structured
Domain names are read from right to left, from the most general part to the most specific:
- The root is the invisible dot at the end of every name (
shop.example.in.). It sits at the top of DNS. - The top-level domain (TLD) is the last label:
.in,.com,.org. Country-code TLDs such as.inalso have second-level extensions such as.co.inand.org.in. - The second-level domain is the name you register:
exampleinexample.in. Together they make your domain,example.in. - Subdomains are anything to the left:
shopinshop.example.in, orwww. You create them yourself in DNS, free of charge.
For registering a name, see the ultimate guide to domain name registration.
4. IP addresses
Computers find each other by IP address, not by name. An IPv4 address is four numbers from 0 to 255, such as 203.0.113.10; an IPv6 address is longer and written in hexadecimal, such as 2001:db8::10. Many sites have both. Several websites can share one IP address: the browser sends the host name with its request (and in the TLS handshake), so the server knows which site you want.
5. DNS: turning the name into an address
The browser needs the IP address for the host name. It asks in order, stopping at the first fresh answer:
Each answer carries a TTL (time to live) that says how long it may be cached. That is why DNS changes take time to be seen everywhere. The full explanation, with record types, is in what is the DNS, and propagation is covered in understanding DNS propagation.
6. Connecting and securing: TCP, QUIC and TLS
With the IP address, the browser opens a connection:
- HTTP/1.1 and HTTP/2 run over TCP, which starts with a three-way handshake: the browser sends SYN, the server replies SYN-ACK, the browser sends ACK.
- HTTP/3 runs over QUIC, which uses UDP and combines the connection and encryption setup into fewer round trips. Browsers try it when the server advertises support, and fall back to TCP otherwise.
Then TLS secures the connection. The server presents its certificate, the browser checks that it is valid, unexpired and issued for this exact host name, and both sides agree on encryption keys. TLS 1.3 does this in one round trip. If the check fails, you see a certificate warning instead of the site. The URL's path and query travel inside the encrypted connection; the host name itself is usually visible to the network.
7. The request and the response
The browser sends a request such as:
GET /products/shoes?colour=black HTTP/2
Host: shop.example.in
Accept: text/html
Cookie: session=...The server answers with a status code, headers such as Content-Type and Cache-Control, and the body. Status codes come in five classes:
| Class | Meaning | Common examples |
|---|---|---|
| 1xx | Informational | 103 Early Hints |
| 2xx | Success | 200 OK |
| 3xx | Redirect | 301 moved permanently, 302 found, 304 not modified |
| 4xx | Problem with the request | 403 forbidden, 404 not found, 429 too many requests |
| 5xx | Problem on the server | 500 internal error, 502 bad gateway, 503 unavailable, 504 gateway timeout |
For what each code means on cPanel and DirectAdmin hosting and how to fix it, see understanding and resolving HTTP status codes.
8. How the browser renders the page
The HTML that arrives is only text. The browser turns it into a page in stages:
- DOM.It parses the HTML into the Document Object Model, a tree of every element. It starts before the whole file has arrived.
- CSSOM.It parses the CSS into a second tree of styles. CSS blocks rendering, because the browser won't draw a page it can't style.
- JavaScript.A normal
scripttag pauses HTML parsing while it downloads and runs. Scripts markeddeferorasync, or modules, don't block parsing. - Render tree.It combines the DOM and CSSOM into the visible elements with their styles. Elements hidden with
display: noneare left out. - Layout.It calculates the size and position of every element for the current screen width.
- Paint and composite.It fills in pixels, text, colours and images, in layers, and combines the layers on screen.
When JavaScript changes the page later, the browser repeats layout and paint for the parts affected. Heavy scripts, large images and fonts that load late are why a page can appear quickly but take a while to become usable.
9. What is inside a browser
10. What this means for your own website
Each step is a place where a site can fail or slow down, and each failure looks different:
- "Server not found" or
DNS_PROBEerrors: the DNS step. Check that your domain points at your hosting; see how do I change my nameservers. - Certificate warnings: the TLS step. Domain India hosting includes free SSL certificates, which are issued once the domain points at the server.
- 4xx and 5xx pages: the server step, usually permissions,
.htaccessrules or application errors. - Slow pages that do load: usually server time or rendering. See my website is slow.
Open the developer tools (F12), go to the Network tab and reload a page. You can see each request, its status code and its timing, split into DNS lookup, connection, TLS, waiting for the server and download.
Frequently asked questions
What happens when I type a URL into a browser?
The browser parses the address, looks up the domain's IP address through DNS, opens a connection to the server, secures it with TLS, sends an HTTP request and receives the page. It then builds the DOM and CSSOM, runs JavaScript, calculates the layout and paints the page on screen.
What is the difference between a domain name and an IP address?
An IP address is the numeric address computers use to reach a server, such as 203.0.113.10. A domain name is the readable name people type. DNS connects the two.
What is the top-level domain in shop.example.in?
.in is the top-level domain, example is the second-level domain you register, and shop is a subdomain that the domain owner creates.
Why do DNS changes not show up immediately?
Every DNS answer carries a TTL that lets browsers, devices and resolvers cache it. Until the cached copy expires, some visitors still get the old answer.
What is the difference between HTTP/2 and HTTP/3?
Both carry the same requests and responses. HTTP/2 runs over TCP. HTTP/3 runs over QUIC, which uses UDP and sets up the connection and encryption in fewer round trips, which helps on slow or unstable mobile networks.
Why does a page appear but stay unresponsive for a while?
The browser can paint content before all JavaScript has finished downloading and running. Large or blocking scripts delay the moment the page responds to taps and clicks.
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