What is Web and How it Works?

We hear “Web”, sometimes as “World Wide Web”. But generally we actually don’t know what the web is? how web works? Let’s talk about the story of the web…

What is Web?

The Web, known as the World Wide Web is a part of the Internet. The Internet is a combination of all of the networks around the world.  Web resources are accessible over the Internet. People who use browsers can access the web resources. Well, but what are the web resources?

Web resources actually are the internet sites. All of the data transferred with HTTP protocol are web resources. For example; pages, images, texts, hyperlinks etc. To access the web resources users have to use browsers. Also you can reach the web resources with some command line tools such as cURL but you can’t see the GUI output of the web resources.

What is a Web Application?

We talk about “how the web works” but we should know first what is a web application?.

Web applications (sometimes called as websites) are applications that are running on the web and use web resources. People need browsers to access web applications and sometimes they need the Internet.

Facebook, Instagram or Youtube, all of these are web applications. You have to connect to the Internet to access these web applications. But you can host your own web application on your system. At this time, you don’t need Internet access to reach the web application since you already have the needed web resources on your PC.

How Website Works?

Websites (web applications) provide some services for people. Let’s think about Facebook. Why do we use facebook? We use it since it connects us and our friends. Or think about Google. It provides connections to other websites over the internet for us.

How a website works is an essential question to understand web application security. Let’s explain.

How Web Works?

When you write en.sibersaldirilar.com, what happens?

When you write en.sibersaldirilar.com to your URL bar, your browser first checks your hosts file. Hosts file consists of IP addresses and domains (they can be only one word). You can see a hosts file sample in the figure below.

Hosts file located on /etc/hosts on Linux and Windows “c:\Windows\System32\Drivers\etc\hosts”. If your hosts file includes an IP for  en.sibersaldirilar.com, your browser goes to the specified IP address. If there is no configuration for en.sibersaldirilar.com on your hosts file, your PC asks “where is en.sibersaldirilar.com” to your DNS server. If you are on a company network and there is a DNS server in your company, first this DNS answers this question. If there is no DNS server or you are using your PC on your home your ISP’s DNS server answers your question.

DNS provides the IP address of the en.sibersaldirilar.com, then your browser requests the web resources of en.sibersaldirilar.com from the specified IP address. (Actually It asks to the web server thar running on specified IP address).