How does HTTP work?

Almost every URL that you use starts with HTTP or HTTPs. Have you ever wondered what it is and how does it work. This blog will help you understand how does HTTP work.

This article covers how does HTTP work. But before we dive into it let’s start with HTTP, also called Hypertext Transfer Protocol. HTTP is a collection of guidelines for sending files over the internet, including text, pictures, sound, video, and other multimedia assets. A user starts using HTTP as soon as they open their web browser. The TCP/IP protocol family, which serves as the internet’s building block, is built upon HTTP application protocol. The most recent HTTP version is HTTP/2, released in May 2015. It is a replacement for HTTP 1.1, but it does not render that protocol obsolete.

Table of contents

Below are the topics covered in this blog:

• How does HTTP work
• Difference between HTTP v/s HTTPs
• HTTP requests and responses
• HTTP Proxies for working

How does HTTP work

The HTTP protocol transfers resources across the internet between the client devices and servers. Client devices ask servers for the resources required to load a web page; hence the servers respond by sending the client devices the requested resources. Sub-documents, such as information on graphics, text, text layouts, etc., that are shared by requests and responses are put together using a client web browser for showing the entire web page file.

Let us understand How does HTTP work with a scenario below:

Consider the internet like a road. The client, or your home, is at one end of the street. The server, a store where you wish to make a purchase, is at the opposite end of the street. Let us understand the basic technicalities in the scenario now:

• The web connection: It allows for online data transmission and reception. It is similar to the roadway between your home and the store.
• TCP/IP: These are two simple communication protocols that specify how data should move through the Internet. They are comparable to the transit systems that allow you to place an order, visit the store, and purchase your items. In our scenario, they are comparable to a car or a bike or any commuter that helps you move around.
• Domain Name System: A website’s address book is analogous to the DNS. When you enter a website address into your browser, it first searches the DNS to determine the IP address of the requested website before retrieving it. For the browser to send HTTP communications to the correct location, it has to determine which server the website is hosted. This is similar to moving around to search for a store’s address and find stuff. 
• HTTP: In the above scenario, it acts as a language for ordering the store’s stuff and for communicating between the server and the client.

A web server includes an HTTP daemon, a software that watches for HTTP requests and then responds to them when they come in addition to the files provided on the web page. An HTTP client requesting the information from servers is a web browser. The browser creates an HTTP request and sends it to the Internet Protocol address specified by the URL when a user enters file requests by either entering a URL to “open” a web file or clicking on a hypertext link. The HTTP daemon receives the request on the target server, which then returns the files which are requested.

In the above image to show how does HTTP works, the user sends the “GET” request to the server that hosts the web address once the user fills in the address. The GET request, which is made via HTTP, informs the server that the user is trying to find the HTML code that defines the structure and appearance of the login page. The login page’s text is contained in the HTML response, while the page’s graphics and videos are requested through separate HTTP requests and the responses. It will take longer for the server to answer queries and for the user’s system to load the page when more requests are made, such as when a page with many photos is called.

TCP/IP is used to compress and transfer information into tiny elements of binary sequences of 1’s and 0’s when these requests and the response pairs are sent. Physical transmission of these packets occurs across electric and fiber-optic cables and wireless networks.

ASCII code makes up the requests and responses that clients and servers will use to exchange data. Requests specify the data the client wants the server to provide, while answers contain code that the client browser will interpret as a web page.

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Difference Between HTTP v/s HTTPs

Click here to read this blog on the difference between HTTP and HTTPs (covered in detail).

HTTP requests and responses

A message is a name given to each exchange between the client and server. Requests or retorts are HTTP messages. Servers receive HTTP requests from client devices and respond by providing HTTP replies to the clients.

HTTP requests

When a client computer, like an internet browser, requests the data from the server to load the webpage, this occurs. The request gives the server the necessary data to customize its reply for the client device. Each HTTP request includes data that has been encoded, including:The particular version of HTTP was then used. The two types are HTTP and HTTP/2.

• A URL: This provides a link to the online source. A technique for HTTP. This specifies the precise response the request anticipates getting from the server.
• HTTP Method: This information includes the type of browser being used and the information they request asks the server for. Additionally, it might contain cookies, which keep track of data previously transmitted by the server processing the request.
• HTTP Header: This information includes the type of browser being used and the information they request asks the server for. Additionally, it might contain cookies, which keep track of data previously transmitted by the server processing the request.
• HTTP Body: This is optional data that the server requires from the request, including user forms submitted to the website by users (such as username/password logins, brief responses, and file uploads).

HTTP Responses

The HTTP response message is the data a client device receives from the web server. As its name suggests, the response is the server’s reply to an HTTP request. The information contained in an HTTP response is tailored to the context the server received from the request. HTTP responses typically include the following data:

• HTTP Status body: It indicates the request’s status to the client device. Responses may indicate success, an informational response, a redirect, or errors on the server or client side.
• HTTP response header: It sends details about the host and the resources that were requested.

HTTP Proxies for working

The application-layer servers, computers, or other units that sit between a client device and the server are proxies or proxy servers in between client and server, proxies transport HTTP requests and answers. Typically, each client-server interaction involves one or more proxies.

Proxy servers can be transparent or opaque. The client’s request is sent to the server unchanged by transparent proxies, who deliver it to the server in its initial form. Non-transparent proxies will in some way alter the client’s request. Non-transparent proxies may be utilized for extra functions frequently to speed up server retrieval.

The developers can make use of proxies for the following:

• Caching: Web pages and other internet content can be saved locally by cache servers to speed up content retrieval and lower the load on the site’s bandwidth.

• Authentication: regulating user rights for online information and applications.
• Logging: keeping old information, like the IPs of users who made requests to the server.

• Web filtration-It limits access to websites that may contain offensive information or undermine security.

• Balanced load: There can be more than one server handling client requests to the server.

Conclusion

The above article discusses HTTP, a collection of guidelines for sending files over the internet, including text, pictures, sound, video, and other multimedia assets. We have also discussed How does HTTP work, its components, and how it differs from HTTPS. We have also discussed the proxies of HTTP, such as caching, authentication, loading, etc. 

Author: Megha Chadda