Internet Essentials

1. Internet Essentials

2. The History of the Internet • The Internet started when the Advanced Research Projects Agency (ARPA) of the United States Defense Department began a network called ARPANET in 1969. • It was used as a tool to link university and government research centers together to exchange information and share resources. 

3. Father of the World Wide Web • In 1990, Tim Berners-Lee produced the first version of the World Wide web, the first web browser and the first web server. • In 1991 it was put online • The first web page address was http://info.cern.ch/hypertext/WWW/TheProject.html

4. WC3 • In 1994, Berners-Lee founded W3C (World Wide Web consortium) • This is an organization to try to improve the quality and standard of the world wide web. 

5. Internet definition • The Internet is a global wide area network that connects computer systems across the world. • It includes several high-bandwidth data lines that makeup the Internet "backbone." • These lines are connected to major Internet hubs that distribute data to other locations, such as web servers and ISPs.

6. Networks • The Internet is the largest computer network in the world, connecting millions of computers. • A network is a group of two or more computer systems linked together.

7. 2 types of Networks • There are two main types of computer networks: 1. Local Area Network (LAN): A LAN is 2 or more connected computers sharing resources in a small geographic location. Examples: home networks and office networks. 2. Wide Area Network (WAN): A WAN is two or more LANs. The computers are farther apart. Examples: OCPS • The Internet is the largest Wide Area Network (WAN) in existence.

8. Servers • A server is a computer that "serves" many different computers in a network by running specialized software and storing information. • For example, webpages are stored on servers.

9. The Cloud • When something is in the cloud, it means it is stored on servers on the Internet instead of on your computer. • It lets you access your calendar, email, files, and more from any computer that has an Internet connection.

10. Packets • Most data moves over the Internet through packet switching. • Suppose you send an email to someone in China. Instead of opening up a long and convoluted circuit between your home and China and sending your email down it all in one go, the email is broken up into tiny pieces called packets. • Each one is tagged with its ultimate destination and allowed to travel separately. • In theory, all the packets could travel by totally different routes. • When they reach their ultimate destination, they are reassembled to make an email again. • Packet switching is efficient because you don't have to have a permanent connection between the two places that are communicating, so you're not blocking an entire chunk of the network each time you send a message. • Many people can use the network at the same time and since the packets can flow by many different routes, depending on which ones are quietest or busiest, the whole network is used more evenly—which makes for quicker and more efficient communication all round.

11. Packets Example • what if you dismantled your home, numbered all the bricks, put each one in an envelope, and mailed them separately to Africa? • All those bricks could travel by separate routes. • Some might go by ship; some might go by air. Some might travel quickly; others slowly. • But you don't actually care. All that matters to you is that the bricks arrive at the other end, one way or another. • Then you can simply put them back together again to recreate your house. • Mailing the bricks wouldn't stop other people mailing things and wouldn't clog up the roads, seas, or airways. Because the bricks could be traveling "in parallel," over many separate routes at the same time, they'd probably arrive much quicker. • This is how packet switching works. When you send an email or browse the Web, the data you send is split up into lots of packets that travel separately over the Internet.

12. Protocols • http://www.explainthatstuff.com/internet.html • The real Internet doesn't involving moving home with the help of envelopes—and the information that flows back and forth can't be controlled by people like you or me. That's probably just as well given how much data flows over the Net each day—roughly 3 billion emails and a huge amount of traffic downloaded from the world's 250 million websites by its 2 billion users. If everything is sent by packet-sharing, and no-one really controls it, how does that vast mass of data ever reach its destination without getting lost? • The answer is called TCP/IP, which stands for Transmission Control Protocol/Internet Protocol. It's the Internet's fundamental "control system" and it's really two systems in one. In the computer world, a "protocol" is simply a standard way of doing things—a tried and trusted method that everybody follows to ensure things get done properly. • So what do TCP and IP actually do? • Internet Protocol (IP) is simply the Internet's addressing system. All the machines on the Internet—yours, mine, and everyone else's—are identified by an Internet Protocol (IP) address that takes the form of a series of digits separated by dots or colons. If all the machines have numeric addresses, every machine knows exactly how (and where) to contact every other machine. When it comes to websites, we usually refer to them by easy-to-remember names (like www.explainthatstuff.com) rather than their actual IP addresses—and there's a relatively simple system called DNS (Domain Name System) that enables a computer to look up the IP address for any given website. In the original version of IP, known as IPv4, addresses consisted of four pairs of digits, such as 12.34.56.78 or 123.255.212.55, but the rapid growth in Internet use meant that all possible addresses were used up by January 2011. That has prompted the introduction of a new IP system with more addresses, which is known as IPv6, where each address is much longer and looks something like this: 123a:b716:7291:0da2:912c:0321:0ffe:1da2. • The other part of the control system, Transmission Control Protocol (TCP), sorts out how packets of data move back and forth between one computer (in other words, one IP address) and another. It's TCP that figures out how to get the data from the source to the destination, arranging for it to be broken into packets, transmitted, resent if they get lost, and reassembled into the correct order at the other end.

13. Operating Systems • The program that lets you interact with your computer • It is software that communicates with the computer hardware (acts like a translator) • Before you connect with the internet you need certain software and hardware installed on your computer • https://www.youtube.com/watch?v=pTdSs8kQqSA&index=2&list=PL4316FC411AD077AA

14. Internet Service Provider (ISP) • Companies that provide service to the internet free or for a fee • Examples: BrightHouse, Century Link, AOL

15. Connecting to the Internet • https://www.youtube.com/watch?v=hMX6dVa61t0

16. Internet Addresses • The internet and the post office have similarities • The internet relies on an addressing system, like the post office, to send data to a computer at a certain destination • An Internet Protocol address (IP) is a number that uniquely identifies each computer • All IP addresses used on the internet are combinations of numbers instead of names • A domain name is the text version of an IP address • https://www.youtube.com/watch?v=qv0XCaUkfNk

17. Domain Names • When you use a mobile phone and select “mom’s home phone” from your address book, you are actually dialing a combination of numbers. This is how domain names work with Web pages.

18. Domain Name Server (DSN) • https://www.youtube.com/watch?v=3xnv-SGad5k • when you specify a domain name, a DNS server translates the domain name to its related IP address so that information is transmitted to the correct computer. • the right-side component of a domain name categorizes domains into groups by company (.com), educational institution (.edu), organization (.org) or country (for example, .ca). These categories are called top-level domains (TLDs). • each domain name is unique and registered with the Internet Corporation for Assigned Names and Numbers (ICANN). • when a name (for example, google) within a domain category (for example, .com) is assigned, no other organization or individual can use that name within that category.

19. Domain Names

20. The World Wide Web • World Wide Web” and “Internet” are often used interchangeably, but they are actually different. • The World Wide Web (WWW or Web) is a service of the Internet. • And the Internet offers many services other than the World Wide Web. These services include e-mail, mailing lists, instant messaging, chat rooms, VoIP, file transfers and newsgroups. • the World Wide Web consists of globally posted electronic documents called Web pages, which can contain text, graphics, links, audio, and video.

21. Web Browsers • A Web browser is a software application that enables your computer to retrieve and display Web pages. The browser’s main function is to present the Web resource that you choose by requesting it from its server and displaying it in your browser window. • https://www.youtube.com/watch?v=n8neFZwd9eE

22. Most Common Web Browsers

23. Web Browsers • the browser retrieves and displays a starting Web page, sometimes called the browser’s home page. • how long it takes for a Web page to load depends on the speed of your Internet connection and the amount of graphics on the page. • https://www.youtube.com/watch?v=N5LQhuD1FPY

24. The process of opening a web browser

25. Web Addresses • A Web page has a unique address, called a Web address or URL (Uniform Resource Locator). A Web browser retrieves a Web page using the page's Web address. When you enter a Web address in a browser, you are requesting information from a Web server. • http://www.cnet.com/Content/Reports

26. Servers and Clients • all of the machines on the Internet can be categorized as two types: servers and clients.  • Those machines that provide services (like Web servers or FTP servers) to other machines are servers. • the machines that are used to connect to those services are clients. • When you connect to Google at www.google.com to do a search, Google is providing a server. You are the client • A machine can be both a server and a client

27. File Transfer Protocol (FTP) • The protocol (or instructions) for exchanging files over the Internet. • FTP is most commonly used to download a file from a server using the Internet or to upload a file to a server (e.g., uploading a Web page file to a server).