What is a web server?

The term ‘web server’ is commonly used to refer both to the physical computer on which the websites are stored and to the software that actually delivers such data.

Web Server ( Computer )

Every website is hosted on a computer usually called server or web server, hardware configuration can be extremely simple or extremely complicated, consisting of groups of multiple servers ( clusters ) sharing the load of requests.

A web server can be a computer very similar to your home computer ( Tower Servers ), or a computer with a case specific for data center usage ( Rack Servers ). These servers can be easily mounted inside racks to optimize space. These servers are usually wide, deep and very thin. The width is 19 inches, it’s standard so that servers can be mounted in any server rack. Servers can be different in height. The base unit used to measure web server space is the Rack Unit, commonly referred to as U, 1.75 inches. Most common sizes for servers are 1U, 2U and 4U depending on the size and number of the components used inside the server.

In the image above you see the difference between tower servers on the left and rack servers on the right ( the black ones, 2U each in this example ).

Actually there’s no difference for you between the two types of servers, the difference can only be measured in terms of space used inside the server farm.

Web Server ( Software )

When we refer to a web server as a software we mean that program that actually delivers the content of your website. It’s a piece of software that waits for requests of web pages and, when such requests arrive, retrieves the page and sends the content to the browser from which the request has been made. In case of static websites the task of the web server is merely serving the static content, instead if the website is dynamic the web server software uses additional modules and functions to deliver the content. What does it mean? It’s easier to explain with an example.

Let’s say we have a database of events with dates and cities, and a dynamic page events.php written in PHP: the visitor sends a request ( clicking a link or submitting a form ) searching for events in Boston on Dec 18, let’s assume that the resulting url from this request is www.yourdomain.com/events.php?city=boston&month=12&day=18 ( understanding this url is out of the scope of this guide, you’ll learn more about this as soon as you decide to learn a scripting language ): the web server receives this request and executes the php program written in the page events.php; this program retrieves the events in Boston on December 18 and format such events in HTML. Done that the web server sends the resulting HTML code to the browser.

The most popular web servers are Apache on unix/linux based systems, Microsoft IIS on Windows systems.

In these guides, when you find the term ‘web server’ we usually refer to the computer on which your website is stored, and not the software that is actually delivering the content.

In the next part of this guide on the basics of web hosting you’ll learn more about domain names.

What is a domain name? ( this guide will be published shortly, subscribe via rss or email using the top left buttons to be notified when it’s online )

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