A web server is a software or hardware system that transmits, stores, and manages web content over the Internet to users' browsers. Its primary function is to deliver web pages and other content based on user requests. Web servers operate through protocols such as HTTP (Hypertext Transfer Protocol) and HTTPS (HTTP Secure). The functioning of a web server is based on the interaction between the client (browser) and the server.
The working principle of a web server consists of a series of steps and protocols that facilitate interaction between the client and the server. This process is designed to enable users to access web pages.
The operation of a web server begins when users enter a specific URL (Uniform Resource Locator) into their web browsers. For instance, when typing an address like "www.example.com," the browser analyzes the URL and identifies the domain name portion. This request from the user leads the client to send an HTTP request to the web server. The HTTP request specifies the type of content the user is requesting and usually comes in the form of a GET request. At this stage, the browser performs a DNS (Domain Name System) query to determine the necessary IP address of the server where the requested resource is located.
A DNS query is the process of translating the domain name entered by the user into the corresponding IP address of the relevant web server. The user's browser sends a query to a DNS server, which scans its cache for previously recorded DNS entries to find the IP address associated with the domain name. This process typically occurs within a few milliseconds, and the browser is then ready to direct its HTTP request to the obtained IP address.
Using the acquired IP address, the browser establishes a connection to the web server. At this stage, the browser creates a TCP (Transmission Control Protocol) connection to the server. TCP provides a reliable communication channel, ensuring the correct delivery of data packets. Once the connection is established, the browser sends the HTTP request to the server. This request begins with the “GET” method and specifies the exact resource or file the client is requesting. The structure of the request may include not only the requested file but also browser information, user identifiers, and other data elements.
Upon receiving the incoming HTTP request, the web server initiates a series of processes configured to handle the relevant operations. First, the server accepts the request and analyzes the HTTP headers. Depending on the content of the request, the server decides whether to serve a static file or dynamic content. For static content, the server locates the requested file in its file system and prepares it for direct response. When dynamic content is requested, the server typically consults an application server or database. During this stage, the server executes a specific program or sends a query to obtain the results, which it then processes to prepare the response.
The web server generates an HTTP response containing the result of the processed request. This response includes not only the content but also a status code. For example, the "200 OK" status indicates that the request was successfully processed, while "404 Not Found" indicates that the requested resource could not be located, and "503 Service Unavailable" signifies server overload. The server sends the generated response back to the client via the HTTP protocol. At this stage, the response is typically formatted in text form (HTML, JSON, XML, etc.) and transmitted to the client.
The browser receives the response from the server and processes it. This process involves analyzing HTML and CSS files, executing JavaScript, and constructing the user interface. The browser renders the response, meaning it formats the content for presentation to the user. When users interact with the page—such as clicking on links or filling out forms—a new HTTP request is generated. This cycle enables the web browser to maintain ongoing interaction between the user and the web server.