The Web

Internet:

The internet is a network of linked computers from around the globe. Each of these computers communicate with each other in a specific format.

Packets:

Packets are the information of the internet. Packets are sent from the sender to the receiever in a specific format which contains all the information needed to communicate.

The differences between a webpage, web server, web browser and search engine:

• A webpage is the page you look at in your browser.
• A web server is the computer that has the code for how the webpage should look and act.
• A web browser is a program on a computer that displays the web page.
• A search engine is a web server that searches all other web servers for information. A user can then pull up the webpage on their web browser and search for a site.

Clients:

A client is the computer or internet device that requests information from the server.

Server:

A server is the computer that receives requests (as packets) from the client and responds with the appropriate data.

DNS Servers:

DNS Servers are the "phone book" of the internet. They translate IP addresses into domain names.

Your typical interaction with the Internet starts with a web browser when you:

1. Enter an address like http://www.google.com into your web browser.
2. Your request is sent to your devices' network interface.
3. The request goes over the Internet where a search for http://www.google.com begins. Behind the scenes, http://www.google.com is simply a human-friendly name that represents an IP Address associated with a remote computer or a server.
4. The remote server accepts the request and sends a response over the Internet to your network interface which hands it to your browser.
5. Finally, the browser displays the response in the form of a web page.

The main thing you must understand is that when your browser issues a request, it's simply sending some text to an IP address. Because the client (web browser) and the server (recipient of the request) have an agreement, or protocol, in the form of HTTP, the server can take apart the request, understand its components and send a response back to the web browser. The web browser will then process the response strings into content that you can understand.

The address you entered, http://www.google.com is known as a Uniform Resource Locator or URL. A URL is like that address or phone number you need in order to visit or communicate with your friend. A URL is the most frequently used part of the general concept of a Uniform Resource Identifier or URI, which specifies how resources are located.

URL Components

When you see a URL, such as "http://www.example.com:88/home?item=book", it's comprised of several components. We can break this URL into 5 parts:

1. http: The scheme. It always comes before the colon and two forward slashes and tells the web client how to access the resource. In this case it tells the web client to use the Hypertext Transfer Protocol or HTTP to make a request. Other popular URL schemes are ftp, mailto or git.
2. www.example.com: The host. It tells the client where the resource is hosted or located.
3. :88 : The port or port number. It is only required if you want to use a port other than the default.
4. /home/: The path. It shows what local resource is being requested. This part of the URL is optional.
5. ?item=book : The query string, which is made up of query parameters. It is used to send data to the server. This part of the URL is also optional