What Happens During an HTTPS Request?

When you visit a website using HTTPS, your browser does more than simply send an HTTP request to a server. It first establishes a secure connection that helps protect the communication between your browser and the website.

HTTPS combines HTTP with Transport Layer Security, commonly called TLS. TLS provides encryption, authentication, and protection against unauthorized modification of data while it travels across the network.

The process involves several steps, including finding the server, establishing a network connection, negotiating TLS security, validating the server's certificate, and finally exchanging encrypted HTTP data.

What Is HTTPS?

HTTPS stands for Hypertext Transfer Protocol Secure. It is HTTP communication protected by TLS.

HTTP defines how browsers and servers exchange requests and responses. TLS protects that communication while it travels between the two endpoints.

What Does HTTPS Protect?

HTTPS is designed to provide three important security properties.

1. Confidentiality

Encryption helps prevent people monitoring the network from reading the contents of protected HTTP traffic.

2. Integrity

TLS provides mechanisms that allow the endpoints to detect unauthorized modification of protected data during transmission.

3. Authentication

TLS certificates allow the browser to verify that the server is authorized for the domain it is connecting to, assuming certificate validation succeeds.

HTTPS Does Not Mean the Website Is Safe

HTTPS protects the connection between the browser and the server, but it does not guarantee that the website itself is trustworthy.

A malicious website can also use HTTPS. The lock icon or HTTPS connection primarily tells you that the connection is protected and that certificate validation succeeded; it does not guarantee that the content, business, or person behind the website is legitimate.

Step 1: You Enter an HTTPS URL

Suppose you enter a URL such as https://example.com/account into your browser.

The browser identifies https as the scheme and understands that the connection should use HTTPS.

It also identifies the hostname, path, and other URL components needed to make the request.

Step 2: DNS Resolves the Domain

Before communicating with the server, the browser generally needs to determine the network address associated with the hostname.

DNS, or the Domain Name System, provides this mapping.

The result may come from a browser, operating system, local network, or DNS resolver cache. If a suitable cached result is unavailable, a DNS lookup may involve additional DNS infrastructure.

Step 3: The Browser Establishes a Network Connection

The next step depends on the HTTP version and transport protocol being used.

HTTP/1.1 and HTTP/2 commonly use TCP as their transport, while HTTP/3 uses QUIC, which operates over UDP.

HTTPS With TCP

When HTTPS is used with TCP, the browser first establishes a TCP connection with the server.

TCP provides reliable and ordered delivery of data between the browser and server.

HTTPS With QUIC

HTTP/3 uses QUIC instead of TCP. QUIC provides transport features such as reliable streams and connection establishment while being implemented over UDP.

The exact connection process therefore differs between traditional HTTPS deployments and HTTP/3.

Step 4: The TLS Handshake Begins

After the necessary transport connection is available, TLS establishes the secure communication channel.

The browser and server exchange information to negotiate cryptographic parameters and establish shared secrets that can be used to protect application data.

What Is a TLS Handshake?

A TLS handshake is the process through which the client and server establish the parameters and cryptographic material needed for secure communication.

It also allows the server to prove its identity using a digital certificate.

Step 5: The Browser Sends a ClientHello

The browser begins the TLS negotiation by sending a ClientHello message.

This message contains information such as supported TLS versions, cryptographic options, and other parameters needed to negotiate a secure connection.

Step 6: The Server Responds

The server responds with the information required to continue the TLS handshake.

It selects compatible cryptographic parameters and provides its certificate chain so that the browser can authenticate the server.

What Is a Digital Certificate?

A TLS certificate is a digitally signed document that binds a public key to information about a domain or other identity.

Certificates are issued by trusted certificate authorities and contain information that allows clients to determine whether the certificate is valid for the requested hostname.

Step 7: The Browser Validates the Certificate

The browser checks several properties of the certificate and its chain of trust.

Hostname

The certificate must be valid for the hostname being accessed.

Validity Period

The certificate must be within its valid time period.

Certificate Chain

The browser verifies that the certificate chain leads to a trusted root certificate according to its trust store and validation rules.

Digital Signatures

The browser verifies the signatures used to establish trust in the certificate chain.

What Is a Certificate Authority?

A Certificate Authority, or CA, is an organization trusted to issue and sign digital certificates.

Browsers and operating systems maintain trusted root certificates that form the basis for validating certificate chains.

What Happens If Certificate Validation Fails?

If the browser cannot establish that the certificate is valid and trusted, it can warn the user or block the connection depending on the type and severity of the validation failure.

Common causes include an expired certificate, a hostname mismatch, an untrusted certificate authority, or an invalid certificate chain.

Step 8: Cryptographic Keys Are Established

The browser and server use the TLS handshake to establish shared cryptographic secrets for the connection.

Modern TLS commonly uses public-key cryptography during the handshake and symmetric cryptography for protecting application data.

Why Use Two Types of Cryptography?

Public-key cryptography is useful for authentication and establishing shared secrets, but symmetric encryption is generally much more efficient for protecting large amounts of application data.

Once the handshake establishes the required keys, the connection can use efficient symmetric encryption for the HTTP traffic.

Step 9: The TLS Handshake Finishes

After the browser and server have agreed on the necessary parameters and established the cryptographic state, the secure TLS connection is ready for application data.

At this point, the browser can send HTTP messages through the protected connection.

Step 10: The Browser Sends the HTTP Request

HTTPS does not replace HTTP. Instead, HTTP messages are carried through the encrypted TLS connection.

The browser can now send a request such as a GET request for /account.

Request Method

The HTTP method describes the intended operation. A normal webpage navigation commonly uses GET.

Request Headers

Headers can contain information such as accepted content types, cookies, language preferences, caching directives, and other metadata.

Request Body

Some HTTP requests contain a body, such as requests that submit form data or send JSON to an API.

What Does the Network See?

A network observer can generally see that encrypted traffic is being exchanged with a particular network destination, along with some connection metadata, but cannot normally read the protected HTTP request and response contents.

HTTPS does not hide every piece of metadata. Depending on the protocol and network configuration, information such as IP addresses, connection timing, traffic volume, and some hostname-related information may still be observable.

Step 11: The Server Decrypts the Request

The server's TLS implementation receives the encrypted data and decrypts it using the cryptographic state established during the handshake.

The resulting HTTP request is then passed to the appropriate web server, reverse proxy, or application.

Step 12: The Server Processes the HTTP Request

The server determines how to respond based on the URL, HTTP method, headers, authentication state, application logic, and other information.

A dynamic application may query databases or communicate with other services before producing its response.

Step 13: The Server Creates an HTTP Response

The server generates an HTTP response containing a status code, response headers, and usually a response body.

The response might contain HTML, JSON, an image, a stylesheet, JavaScript, or another type of resource.

Step 14: The Response Is Encrypted

Before the response travels back across the network, it is protected by the established TLS connection.

The browser receives encrypted TLS records and processes them using the cryptographic state established during the handshake.

Step 15: The Browser Decrypts the Response

The browser decrypts and verifies the received TLS-protected data.

The resulting HTTP response can then be processed by the browser as normal.

Step 16: The Browser Processes the Content

If the response contains HTML, the browser parses it and may request additional resources such as CSS, JavaScript, images, fonts, and API data.

Those additional requests can also use HTTPS and may reuse existing secure connections.

Does HTTPS Encrypt the Entire Internet Connection?

HTTPS protects the HTTP application data carried over the TLS connection. It does not encrypt every other type of network activity on the device.

Other applications can use different protocols and security mechanisms, and network metadata can remain visible even when application data is encrypted.

Does HTTPS Hide the URL?

HTTPS protects the HTTP request contents, including the path and query information once they are inside the encrypted connection.

However, HTTPS does not necessarily hide all information about the destination. Network-level metadata such as the destination IP address can still be visible, and hostname visibility depends on the protocols and privacy mechanisms being used.

HTTPS vs HTTP

HTTP sends application data without TLS protection, while HTTPS carries HTTP through a TLS-secured connection.

HTTP

Data is not protected by TLS, so an attacker able to observe or modify the network traffic may be able to read or alter the HTTP messages.

HTTPS

TLS provides encryption, integrity protection, and server authentication for the HTTP communication.

Why Is HTTPS Important for Passwords?

When a website uses HTTPS correctly, credentials sent through the protected connection are encrypted while traveling between the browser and server.

Without HTTPS, credentials and other HTTP data could potentially be exposed to attackers who can observe the network traffic.

Does HTTPS Prevent Phishing?

No. HTTPS does not prevent phishing.

A phishing website can obtain a valid certificate and serve its pages over HTTPS. Users still need to verify the domain and consider whether the website itself is trustworthy.

Can Someone Read HTTPS Traffic?

A properly configured HTTPS connection is designed to prevent ordinary network observers from reading the protected application data.

However, HTTPS does not protect data after it reaches an endpoint. A compromised browser, device, server, or trusted intermediary that terminates TLS can potentially access the decrypted information.

What Is TLS Termination?

In many production architectures, TLS is terminated at a load balancer, reverse proxy, CDN, or edge server rather than directly inside the application.

The component terminating TLS decrypts the HTTPS traffic and can then forward the request to backend services using another protected or internal connection.

What Happens With HTTP/2?

HTTP/2 commonly operates over TLS when used on the public web. It allows multiple streams of HTTP communication to share a connection, which can improve efficiency compared with older HTTP/1.1 connection patterns.

What Happens With HTTP/3?

HTTP/3 uses QUIC instead of TCP. QUIC integrates transport and TLS-related connection establishment more closely and supports encrypted HTTP communication over UDP.

The high-level goal remains the same: establish a secure connection and exchange HTTP data while protecting it from unauthorized observation or modification.

Why Can HTTPS Be Fast?

Modern TLS is designed to provide strong security without making web communication impractically slow.

Connection reuse, session resumption, efficient cryptographic algorithms, HTTP/2, HTTP/3, and optimized network infrastructure can reduce the overhead of secure connections.

What Is TLS Session Resumption?

When a browser reconnects to a server it has recently communicated with, TLS can sometimes use session resumption mechanisms to avoid repeating the full cost of establishing a completely new cryptographic session.

The Complete HTTPS Journey

A simplified HTTPS request can be represented as: URL entered → DNS resolution → TCP or QUIC connection → TLS handshake → certificate validation → cryptographic keys established → encrypted HTTP request → server processing → encrypted HTTP response → browser decryption → webpage or data processing.

Why Understanding HTTPS Matters

Understanding HTTPS helps developers diagnose certificate errors, connection problems, API failures, security warnings, and performance issues.

It also explains why HTTPS is more than simply putting a lock icon next to a website address. It is a combination of HTTP, cryptography, certificates, network protocols, and trusted infrastructure working together.

The Future of Secure Web Communication

Web security continues to evolve through newer TLS versions, stronger cryptographic practices, HTTP/3 and QUIC, improved certificate management, privacy technologies, and better browser security controls.

The fundamental goal remains consistent: allow browsers and servers to communicate while making it difficult for unauthorized parties to read or modify the protected application data.

During an HTTPS request, the browser first finds the server, establishes the required network connection, performs a TLS handshake, validates the server's certificate, establishes cryptographic keys, and then sends HTTP data through the encrypted connection.

The simplest way to understand HTTPS is this: HTTP defines the messages exchanged between a browser and server, while TLS creates a protected channel through which those messages travel.

The browser and server authenticate the server, establish shared cryptographic secrets, and then use those secrets to protect HTTP requests and responses from unauthorized reading or modification during transmission.