What happens when you enter a URL in a browser and press Enter? Describe the entire process from DNS resolution to page rendering.

When you enter a URL in the browser and press Enter, the following process occurs:

1. Parsing the URL: the browser breaks down the entered address into parts — protocol, domain, path, etc.

2. DNS resolution: the browser contacts the DNS server to obtain the IP address of the server by its domain name.

3. Establishing a TCP connection: using the IP address, a connection is established with the server via the TCP protocol (usually on port 80 for HTTP or 443 for HTTPS).

4. TLS Handshake (if HTTPS): a secure connection is established using the TLS protocol.

5. Sending the HTTP request: the browser sends a request (GET, POST, etc.) to the server with the required resource.

6. Server processes the request: the server receives the request, processes it (possibly accessing a database, executing logic), and forms a response.

7. Receiving the HTTP response: the browser receives a response with a status code, headers, and body (HTML, JSON, files, etc.).

8. Parsing HTML: the browser starts parsing the HTML document, building the DOM tree.

9. Loading resources: the browser detects links to CSS, JS, images, and other resources, requesting them from the server.

10. Executing CSS and JS: the browser applies styles, executes scripts, which may alter the DOM and visual display.

11. Rendering the page: the browser renders the content on the screen, displaying the page to the user.

12. Handling events: after the page loads, the browser begins processing user events (clicks, input, etc.).

This process happens very quickly, creating the sensation of instant page opening.