# Internet Fundamentals/Printable version

The current, editable version of this book is available in Wikibooks, the open-content textbooks collection, at
https://en.wikibooks.org/wiki/Internet_Fundamentals

# Introduction
## The Internet
### What is the Internet?

* The Internet is a global Wide Area Network (WAN).
** A Network is a group of interconnected devices.
** A Wide Area Network (WAN) is a network that covers a large area.
** A Local Area Network (LAN) is a network that covers a small area.

### What are the main advantages of the Internet?

* Communication : Electronic mail (Email) and social media.
* Education : search engines and webpages.
* Entertainment : online games and online media.
* Online services : online shopping and online banking.

### What are the main disadvantages of the Internet?

* Threat to personal information : possible loss of name, address, credit card number,...
* Spamming : unwanted Emails that serve no purpose.
* Cybercrime : malware, ransomware, stealing of identities,...
* Virus attacks : cause a system to crash and may delete important data.

### History of the Internet

* In the 1950s, the United States Defense Department formed the Advanced Research Projects Agency (ARPA) with the purpose of developing technology.
* ARPA’s scientists could not easily communicate or share information, so they created a network of computers, which they called ARPAnet.
* In the 1970s, the TCP/IP protocol was developed, this protocol allowed the separate networks to communicate with each other.
* The joining of these networks created a huge WAN which came to be known as the Internet.

## The World Wide Web (WWW)
### What is the World Wide Web (WWW)?

* The World Wide Web (WWW) is a collection of different websites that can be accessed through a web browser.
** A website is a group of webpages hosted on one web server.
** A web server is an Internet server that serves webpages to the web browser.
** A web browser is an application that displays webpages.

### What is the difference between the World Wide Web (WWW) and the Internet?

* The Internet is a global WAN, and the WWW is an Internet service.

### How the World Wide Web (WWW) works?

* When a user makes a request over the Internet, the web browser sends this request to a web server, and the web server accepts and responds to it by storing and transferring webpages to the web browser.

### How are web pages transferred from servers to clients?

* Any resource connected to the WWW is identified by its Uniform Resource Locator (URL).
** A Uniform Resource Locator (URL) is the address of a WWW page.
** Example : http://www.example.com/...
* When the URL of a web page is identified, a protocol called Hyper Text Transfer Protocol (HTTP) sends a command to the web server.
** Hyper Text Transfer Protocol (HTTP) is a protocol which enables communication between web clients and web servers.
* Once the web server has transmitted the requested page, the web page can be displayed with Hyper Text Markup Language (HTML).
** Hypertext Markup Language (HTML) is the standard language for creating and displaying web pages.

### History of the World Wide Web (WWW)

* In 1990, the WWW was invented by Tim Berners-Lee.
* He created three technologies (HTML, URL and HTTP), which allowed to use the Internet to link one document directly to another.

## Internet connectivity
### What is needed to connect to the Internet?

* Internet Service Provider (ISP) : a business that provides a connection to the Internet.
* Modem : a piece of hardware that allows a device to connect to the Internet over a telephone line.
* Router : a piece of hardware that allows several devices to connect to a single Internet connection.

### Common methods of Internet connection

* Dial-up : an Internet connection which uses a telephone line and requires a landline.
* Digital Subscriber Line (DSL) : an Internet connection which uses a telephone line, but doesn’t require a landline.
* Cable TV : a wired Internet connection which uses Cable TV lines.
* Wi-Fi : a wireless Internet connection which uses radio waves.
* Satellite : a wireless Internet connection which uses satellites orbiting the Earth.
* 3G, 4G, and 5G : wireless Internet connections which uses cellular networks.

## Cloud computing
### What is cloud computing?

* Cloud computing is the process of storing and using services online, rather than storing them locally on a device.

### What are the main advantages of cloud computing?

* File storage : access files, documents and Emails from any device.
* File sharing : share files with several people at the same time.
* Backing up : protect your files.

### What are the main disadvantages of cloud computing?

* Copyright : possible loss of legal rights.
* Security : vulnerability to security attacks.
* Storage : expense of storage.

# Web browsers
## Web browsers
### What is a Web browser?

* A Web browser is an application that displays Webpages.

### Main functions of a Web browser

* Retrieval : the process of bringing information to the user.
* Display : the process of showing information to the user.
* Navigation : the process of moving around a Website in order to access other information.

### Graphical User Interface (GUI) elements of a Web browser

* Navigation buttons : back, forward, refresh, stop, and home buttons.
** The back button retrieves the previous Web page that referred to the Web page currently viewed.
** The forward button retrieves to the forward Web page and only works if the back button has been previously used.
** The refresh button reloads the Web page that is currently viewed.
** The stop button stops a Web page from loading.
** The home button retrieves the default Web page.
* Address bar : a text field used to input the URL of a Website and display this Website.
* Search bar : a text field used to input terms and display several Websites.
* Status bar : a bar that displays information on the URLs of links and information on the Webpage as it loads.

### Main features of a Web browser

* Tabbed browsing : a form of navigation that allows to have multiple Webpages open at the same time.
* Bookmarks : saved shortcuts that direct to specific Webpages.
* Browsing history : the list of Webpages a user has visited recently.
* Page zooming : the ability to reduce or enlarge the content of a Webpage.
* Downloading : the process of copying data from one device to another.

### Main browser extensions

* Plug-in : an application that adds a specific feature to a program.
** Adobe Flash Player : an application that allows the user to display multimedia on Web browsers.
** Adobe Acrobat Reader : an application that allows the user to display Portable Document Format (PDF) files on a Web browser.
** Microsoft Silverlight : an application that allows a user to use video sites on a Web browser.
* Pop-up blocker : a program that prevents pop-up windows from appearing on a Website.
** A pop-up is an online advertising that uses a new window for display.
* Browser cache : a temporary storage of Web data.
** The main purpose of a browser cache is to speed up Internet surfing by saving Web data, so that when the user tries to go back to recently visited Web pages, the browser displays them instead of downloading them again.
* Cookies : small pieces of data exchanged between the Web browser and the Web server that store information about the user.
** The main purpose of a cookie is to identify the user, prepare custom Web pages and save site login information in order to provide recommendations for the user.

## Hyperlinks
### What is a hyperlink?

* A hyperlink is an element that links either to another place in the same document, or to another document.

### Colors of hyperlinks

* Blue : unvisited link.
* Purple : visited link.
* Red : active link.

### Types of hyperlinks

* Internal : links to a different page in the same Website.
* External : links to another Website.
* Relative : links to a specific place in the same page.

## Uniform Resource Locators (URLs)
### What is an Uniform Resource Locator (URL)?

* An Uniform Resource Locator (URL) is an unique identifier used to locate a resource on the Internet.

### Protocol

* The protocol of an URL determines how data is transferred between the host and a client.

### Hostname

* The hostname identifies the host that holds the resource.
* The subdomain identifies the location of the resource on the Web server.
* The domain name identifies the name of the Website.
* The Top-Level-Domain (TLD) identifies the Website geographical area, or the organization that owns it.

### Path

* The path identifies the specific resource in the host that the client wants to access.

### Query string

* The query string assigns values to specified parameters that the resource can use.

### Anchor

* The anchor identifies the specific location of the resource within a page of the Website.

## Browser extensions
# Search engines

Search engines are used to find specific content on the World Wide Web.
Common search engines as of 2023 include:
* Google
* Bing

## Read More

* The Wikibook How To Search

# Culture

The internet has cultivated a unique culture, one with it's own norms and etiquette. While specific services and websites often have their own distinct culture, there are a few general rules of thumb that apply most places. These fundamentals are often called netiquette.
Common, but not universal, cultural norms online can include:

## Spam

Activities which could be seen as "Spam" should be avoided. These can include unwarranted solicitation of commercial goods, but can also include non-commercial activities, such as sending a large number of messages in quick succession, making nonconstructive posts, or otherwise acting in a way that is seen as detrimental to the community.

## Reviving old threads

Most forms typically look down on or prohibit "reviving" or "necroing" old threads by creating new posts in them.
What counts as an old post depends highly on the specific community, with some considering day old threads to be old news, and others allowing for the posting in threads that are several years old.
Generally, it's OK to post in a thread that has had active commentary recently. If a community has a thread that was started in 2008 and has had active discussion to the present day, it's not reviving that thread, since the thread never "died". However posting in a different thread that was started in 2008 and hasn't seen a post since 2009 would likely be seen as reviving that thread, and a potential breach of netiquitte.