What Is Hypertext Transfer Protocol(HTTP) ? How Does It Work? Complete Guides 2024

Hypertext transfer protocol or HTTP is a fundamental protocol used on the Internet in order to control data transfer to and from a hosting server, in communication with a web browser.

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HTTP is the essential means of communication between web users and the servers that maintain the websites themselves.

As a stateless protocol, HTTP is not inherently saving user settings — so items like cookies are used to help the web sites and servers to “remember” what a user has done.

The use of user-accessible tools means users can choose to erase cookies and other tools and start over again as anonymous users, or save these markers so that they can bypass all of that “getting to know” the hosting server’s site again.

In some ways, HTTP has been useful in transitioning web use into a really stable stateful result — but users who delete all cookies and stored data for the first time may be dismayed by how much of their daily web routine is compromised.

Early HTTP

Let’s talk about some of the essential parts of the HTTP header. HTTP request and response headers define the operating parameters of HTTP transactions.

A request structure typically contains the URL with a method, and defines the protocol.Hypertext Transfer Protocol

Then there are various standard and non-standard request fields that all trigger different interactions.

A simple way to think of this is that the HTTP codes and fields are, again, the way that the two transacting parties communicate — browsers send the request to the server, and the servers send the responses, also in HTTP syntax.

Universalizing this in the context of hypertext syntax makes sense and is a part of how groups like the World Wide Web Consortium or W3C approached building the Internet as it exists today.Hypertext Transfer Protocol

Making HTTP Secure

Over time, a new protocol called HTTPS emerged, which encrypts the contents of HTTP messages with Transport Layer Security and Secure Dockets Layer or TLS/SSL protocols.

Prior to this, in many cases, hackers could simply go in and type in additions or amendments to the actual request in their browser URL bar, before triggering the request itself. That led to all sorts of security vulnerabilities where bad actors were getting control of or access to systems.

Because HTTPS encrypts the actual HTTP syntax, it’s effective in safeguarding against this kind of activity.

Tracking and Interactivity

As the web becomes more complex, HTTP is evolving, too. The ways that web users and sites interact have been subject to some pretty significant evolutions over the last couple of decades.

For example, in general, the era of Web 2.0 has been a time in which company and other websites have become more interactive. There are more user registration fields and other user events embedded in web pages in general, and all of these have to be managed with HTTP, or more accurately HTTPS.

Then there’s the news of a future web 3.0, which will rely on technologies like JSON to accommodate more data mapping, more semantic connection and more automation of browser and server interactions.Hypertext Transfer Protocol

HTTP itself might undergo a lot more future change to accommodate this — but for now, HTTPS remains a foundational aspect of Internet security and function.

• HTTP stands for HyperText Transfer Protocol.
• It is a protocol used to access the data on the World Wide Web (www).
• The HTTP protocol can be used to transfer the data in the form of plain text, hypertext, audio, video, and so on.
• This protocol is known as HyperText Transfer Protocol because of its efficiency that allows us to use in a hypertext environment where there are rapid jumps from one document to another document.
• HTTP is similar to the FTP as it also transfers the files from one host to another host. But, HTTP is simpler than FTP as HTTP uses only one connection, i.e., no control connection to transfer the files.
• HTTP is used to carry the data in the form of MIME-like format.Hypertext Transfer Protocol
• HTTP is similar to SMTP as the data is transferred between client and server. The HTTP Hypertext Transfer Protocol differs from the SMTP in the way the messages are sent from the client to the server and from server to the client. SMTP messages are stored and forwarded while HTTP messages are delivered immediately.

Features of HTTP:

• Connectionless protocol: HTTP is a connectionless protocol. HTTP client initiates a request and waits for a response from the server. When the server receives the request, the server processes the request and sends back the response to the HTTP client after which the client disconnects the connection. The connection between client and server exist only during the current request and response time only.
• Media independent: HTTP protocol is a media independent as data can be sent as long as both the client and server know how to handle the data content. It is required for both the client and server to specify the content type in MIME-type header.Hypertext Transfer Protocol
• Stateless: HTTP is a stateless protocol as both the client and server know each other only during the current request. Due to this nature of the protocol, both the client and server do not retain the information between various requests of the web pages.

HTTP Transactions

The above figure shows the HTTP transaction between client and server. The client initiates a transaction by sending a request message to the server. The server replies to the request message by sending a response message.

What is HTTP (Hypertext Transfer Protocol)?

The Hypertext Transfer Protocol is an application protocol for distributed, collaborative, hypermedia information systems that allows users to communicate data on the World Wide Web.

What is the purpose of HTTP?

HTTP was invented alongside HTML to create the first interactive, text-based web browser: the original World Wide Web. Today, the protocol remains one of the primary means of using the Internet.

How does HTTP work?

As a request-response protocol, HTTP gives users a way to interact with web resources such as HTML files by transmitting hypertext messages between clients and servers. HTTP clients generally use Transmission Control Protocol (TCP) connections to communicate with servers.

HTTP utilizes specific request methods in order to perform various tasks. All HTTP servers use the GET and HEAD methods, but not all support the rest of these request methods:

• GET requests a specific resource in its entirety
• HEAD requests a specific resource without the body content
• POST adds content, messages, or data to a new page under an existing web resource
• PUT directly modifies an existing web resource or creates a new URI if need be
• DELETE gets rid of a specified resource
• TRACE shows users any changes or additions made to a web resource
• OPTIONS shows users which HTTP methods are available for a specific URL
• CONNECT converts the request connection to a transparent TCP/IP tunnel
• PATCH partially modifies a web resource

Security Concerns Around HTTP

Unfortunately, adversaries can choose from many vectors to attack web servers, web applications, and websites. From cross-site scripting (XSS) to HTTP request smuggling, adversaries typically exploit well-known vulnerabilities and misconfigurations—not to mention the HTTP security concerns around sending plaintext credentials via HTTP. The OWASP foundation has highlighted the top 10 security risks to avoid when building web applications, helping improve defenses against HTTP-based attacks.Hypertext Transfer Protocol

Many attacks occur over HTTPS, an encrypted HTTP connection established with SSL/TLS. Learn how monitoring encrypted traffic matters for detecting attacks like Log4j which can hide in encrypted HTTPS traffic.Hypertext Transfer Protocol

Overview of HTTP

HTTP, or Hypertext Transfer Protocol, is the foundation of communication on the Internet. It operates on a client-server model, where the front-end client (such as a web browser) initiates a request, such as requesting a webpage (e.g., a search engine), by sending an HTTP request message to the server. The server then responds with an HTTP response message containing the requested resource or an error message if the resource is not available.

HTTP is a stateless protocol, meaning each request is independent and unrelated to previous or future requests. This allows for efficient communication between clients and servers.Hypertext Transfer Protocol

HTTP was first introduced in 1991 as part of the World Wide Web project created by Tim Berners-Lee and is standardized by the Internet Engineering Task Force (IETF). The IETF is responsible for developing and maintaining protocols such as HTTP, TCP/IP, DNS, and many others that they document in RFCs or “Request for Comments.”

In the early days, there was a need for a standardized protocol that could facilitate communication between different computers and servers. This led to the development of various protocols, including HTTP.

HTTP 0.9, the first version of the protocol, was a simple and limited system that only supported the retrieval of hypertext documents. It had no support for headers, allowing only plain text data to be transferred.

In 1996, HTTP 1.0 was released, introducing several important features still in use today. It added support for multiple media types, allowing for transferring images, videos, and other file formats. It also introduced the use of headers for more advanced functionality, such as caching and authentication.

HTTP 1.1, released in 1999, further improved upon the protocol. It introduced persistent connections, allowing multiple requests and responses to be sent over a single TCP connection. This greatly improved the efficiency and speed of communication between clients and servers.Hypertext Transfer Protocol

In recent years, efforts have been made to enhance and optimize the HTTP protocol. This led to the development of HTTP/2, released in 2015. HTTP/2 brought several improvements, including multiplexing, header compression, and server push, to reduce latency and improve performance.

Finally, there’s HTTP/3. HTTP/3, also known as HTTP over QUIC (Quick UDP Internet Connections), is the latest HTTP protocol version designed to address some of the limitations of previous versions and improve performance.

HTTP/3 is built on top of the QUIC transport protocol, which uses the User Datagram Protocol (UDP) instead of TCP. UDP offers several advantages over TCP, such as reduced latency and improved congestion control. Using UDP, HTTP/3 aims to provide faster, more reliable, and more secure connections.Hypertext Transfer Protocol

One of the key features of HTTP/3 is its ability to support multiplexing and stream multiplexing. This allows multiple requests and responses to be sent concurrently over a single connection, improving efficiency and reducing latency. Additionally, HTTP/3 incorporates features like zero-RTT connection establishment, improved congestion control, and improved security through encryption.

HTTP and Servers

Servers are crucial in handling HTTP requests and serving the corresponding responses. Here are a few key points about the relationship between HTTP and servers:

1. Request-Response Model: As previously mentioned, HTTP follows a request-response model. A client sends an HTTP request to a server, specifying the desired action, such as retrieving a web page or submitting form data. The server processes the request and sends back an HTTP response, which includes a status code, headers, and the requested content (if applicable).
2. Web Servers: Web servers are software applications or programs that handle HTTP requests. They listen for incoming requests on a specific network port (usually Port 80 for HTTP) and route them to the appropriate resources or applications. Popular web server software includes Apache, Nginx, and Microsoft IIS.
3. Routing and Resource Handling: In an HTTP server, routing determines how incoming requests are mapped to specific resources or endpoint handlers. For example, when a request is received for a particular URL or path, the server uses routing rules to determine which code or resource should handle the request and generate the appropriate response.Hypertext Transfer Protocol
4. Processing and Generating Responses: When an HTTP request reaches the server, it triggers the execution of code or resource handlers associated with the requested resource. These handlers can retrieve data from databases, interact with external services, or generate dynamic content. The server processes this data based on the request and generates an HTTP response with the necessary headers and content.Hypertext Transfer Protocol
5. Status Codes: HTTP responses include status codes that indicate the outcome of the request. These status codes range from informational (1xx) to success (2xx), redirection (3xx), client errors (4xx), and server errors (5xx). Common status codes include 200 (OK), 404 (Not Found), and 500 (Internal Server Error).
6. Statelessness: HTTP is a stateless protocol, meaning each request/response interaction is independent and does not retain information about previous requests. To maintain user sessions or track user interactions, servers often use cookies or session management techniques.Hypertext Transfer Protocol

How does HTTP work?

When a client wants to retrieve a web page or new resource from a server, it initiates an HTTP request. This request consists of several components:

• Request Method: The client specifies the desired action it wants the server to perform. The most common method is “GET,” which retrieves a resource, but other methods like “POST,” “PUT,” and “DELETE” are used for various purposes.Hypertext Transfer Protocol
• URL (Uniform Resource Locator): The URL identifies the specific resource the client wants to access. It includes the protocol (HTTP), the server’s domain name or IP address, and the path to the resource on the server.
• Headers: HTTP header fields provide additional information about the request and the client. They can include information such as the user agent (the client application making the request), accepted content types, and cookies. One common example is Content-length. Content-Length specifies the message body size in a request or response. It indicates the length, in bytes, of the entity-body or payload included in the HTTP message.Hypertext Transfer Protocol
• Body (Optional): Some requests may include a body that contains additional data, typically used with methods like “POST” or “PUT” to send data to the server.

Once the client sends the HTTP request, it reaches the server. The server processes the request and generates an appropriate response. The HTTP response consists of several components as well:Hypertext Transfer Protocol

• Status Line: This line includes the HTTP version, a three-digit status code, and a corresponding status message. The status code indicates the outcome of the request, such as 200 for a successful request or 404 for a resource not found.
• Headers: Similar to the request headers, response headers provide additional information about the response and the server. They can include information such as the content type, cache-control directives, and server informationHypertext Transfer Protocol.
• Body: The response body contains the content sent back to the client. For example, the response body would contain the HTML markup if the request was for an HTML web page.

Content Negotiation

Content negotiation is the process by which the client and server communicate their preferences and capabilities regarding content types. This allows for flexibility in delivering the most suitable content for the client.Hypertext Transfer Protocol

The Accept header in the client’s request specifies the content types it can handle, ordered by preference. For example, a client may send an Accept header with “text/html” and “application/json” to indicate that it can handle both HTML and JSON (JavaScript Object Notation) content types. XML is another supported format mentioned in the Accept header, indicating that the client wants to receive the response in XML format.

The server examines the Accept header and compares it to the available content types it can deliver. The server sends the response with the corresponding content type if there is a match. If there is no match, the server may respond with a different content type or return a 406 status code indicating that none of the available content types are acceptable to the client.Hypertext Transfer Protocol