Web server
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Web server
A web server is either the computer (hardware) or the program (software) that delivers web content over the internet.
On the World Wide Web, a web server's main job is to store, process, and deliver web pages and files to your web browser using HTTP. When you go to a website, your browser talks to the web server hosting it.
Client-Server Model
Web servers use a client-server model. Your web browser (the client) sends an HTTP request to the web server, usually asking for a specific web page or image identified by a URL.
The web server constantly listens for requests on specific ports (like 80 for HTTP or 443 for HTTPS). When it gets a request, it processes it and sends an HTTP response. This response contains the requested content (if found) and a status (e.g., '200 OK' for success, '404 Not Found' for errors). Your browser then displays this content.
Software Component
The web server software is the program that handles HTTP requests. It's built to manage many client requests at once.
Web server software is responsible for:
Processing Requests: Receiving and understanding HTTP requests from browsers (e.g., what page or action is asked for). Locating Resources: Finding the requested file or data on the server's storage. Generating Responses: Building the HTTP response, including the content and status information (headers). Web server software can deliver different types of content:
Static Content: Files stored as-is, like HTML, images, CSS, and JavaScript. The server just sends them directly. Dynamic Content: Content generated live by server-side code (e.g., PHP, Python, Java, Node.js) in response to a request. This code can interact with databases or other services before sending HTML back to the client. Common features built into web server software include:
Virtual Hosting: Allows one server to host multiple websites, each with its own domain name. Access Control: Restricts access to files or directories, often requiring login. Logging: Records details of every request (IP, time, URL, status) for monitoring and debugging. TLS/SSL Support: Enables secure, encrypted communication (HTTPS) between browsers and servers, protecting data in transit. Compression: Reduces file sizes (HTML, CSS, JavaScript) before sending to save bandwidth and speed up loading. Caching: Stores frequently used resources in memory for faster delivery.
Examples of Web Server Software
Some of the most widely used web server software applications are:
Apache HTTP Server Nginx Microsoft Internet Information Services (IIS) LiteSpeed Web Server Caddy Web Server
Hardware Component
The hardware component of a web server is the actual computer running the software. It needs to be reliable with enough processing power, memory, and storage for the workload.
Key hardware resources required for a web server include:
Processing Power (CPU): Handles computations for requests, especially for dynamic content and HTTPS encryption. Memory (RAM): Used by the operating system and server software. Sufficient RAM allows many connections and fast content delivery. Storage: Hard drives or SSDs for website files, application code, databases, and logs. Storage speed affects how fast static files are retrieved. Networking: A fast, reliable network connection is crucial for receiving and sending data efficiently. Web server hardware is often in data centers, which provide essential power, cooling, and high-speed, reliable network access.
How it Works
The basic flow when you access a website is:
You type a URL (e.g., https://www.example.com) into your browser. Your browser uses DNS to find the web server's IP address from the domain name. Your browser connects to that IP address, usually on port 443 (for HTTPS). Your browser sends an HTTP request for the URL's content. The web server receives the request, finds the file (static) or runs a script (dynamic). The web server creates an HTTP response with the content and status. The web server sends this response back to your browser. Your browser receives the response, reads the HTML and other files, and displays the page.
Use Cases
Web servers are essential for the World Wide Web and power many online services:
Hosting Websites: Their main role is making websites available online. Web Applications: They deliver content and run server-side logic for interactive web apps (e.g., online stores, social media). APIs: They handle API requests, enabling software systems to communicate and exchange data online. File Sharing: Can serve files directly via HTTP for downloads. Streaming Media: Delivering audio and video content as streams to clients.
