Networking and Communication

The Internet and the World Wide Web

Over the next decade, the ARPANET grew and gained popularity. During this time, other networks also came into existence. Different organizations were connected to different networks. This led to a problem. The networks could not communicate with each other. Each network used its own proprietary language, or protocol (see sidebar for the definition of protocol) to send information back and forth. This problem was solved by the invention of Transmission Control Protocol/Internet Protocol (TCP/IP). TCP/IP was designed to allow networks running on different protocols to have an intermediary protocol that would allow them to communicate. So as long as your network supported TCP/IP, you could communicate with all of the other networks running TCP/IP. TCP/IP quickly became the standard protocol and allowed networks to communicate with each other. It is from this breakthrough that we first got the term Internet, which simply means "an interconnected network of networks".

Sidebar: An Internet Vocabulary Lesson

Network communication is full of some very technical concepts based on simple principles. Learn the following terms and you'll be able to hold your own in a conversation about the Internet.

• Packet The fundamental unit of data transmitted over the Internet. When a host (PC, workstation, server, printer, etc.) intends to send a message to another host (for example, your PC sends a request to YouTube to open a video), it breaks the message down into smaller pieces, called packets. Each packet has the sender's address, the destination address, a sequence number, and a piece of the overall message to be sent. Different packets in a single message can take a variety of routes to the destination and they can arrive at different times. For this reason the sequence number is used to reassemble the packets in the proper order at the destination.
• Switch A network device that connects multiple hosts together and forwards packets based on their destination within the local network which is commonly known as a Local Area Network (LAN).
  
• Router A device that receives and analyzes packets and then routes them towards their destination. In some cases a router will send a packet to another router. In other cases it will send it directly to its destination. Routers are used to connect one network to another network.
• IP Address Every device on the Internet (personal computer, a tablet, a smartphone, etc.) is assigned a unique identifying number called an IP (Internet Protocol) address. Originally, the IPv4 (version 4) standard was used. It had a format of four numbers with values ranging from 0 and 255 separated by a period. For example, the domain Dell.com has the IPv4 address 107.23.196.166. The IPv4 standard has a limit of 4,294,967,296 possible addresses. As the use of the Internet has grown, the number of IP addresses needed has increased to the point where the use of IPv4 addresses will be exhausted. This has led to the new IPv6 standard.The IPv6 standard is formatted as eight groups of four hexadecimal digits, such as 2001:0db8:85a3:0042:1000:8a2e:0370:7334. The IPv6 standard has a limit of 3.4×10³⁸ possible addresses. For example, the domain LinkedIn.com has an IPv6 address of: [2620:109:c002::6cae:a0a]. You probably noticed that the address has only five groups of numbers. That's because IPv6 allows the use of two semi-colons ( :: ) to indicate groups that are all zeroes and do not need to be displayed. For more detail about the IPv6 standard, see this Wikipedia article.
• Domain name If you had to try to remember the IP address of every web site you wanted to access, the Internet would not be nearly as easy to use. A domain name is a human-friendly name, convenient for remembering a website. These names generally consist of a descriptive word followed by a dot (period) and the Top-Level Domain (TLD). For example, Wikipedia's domain name is wikipedia.org. Wikipedia describes the organization and .org is the TLD. Other well-known TLDs include .com, .net, and .gov. For a list and description of top level domain names, see this Wikipedia article.
• DNS DNS stands for "domain name server or system". DNS acts as the directory of websites on the Internet. When a request to access a host with a domain name is given, a DNS server is queried. It returns the IP address of the host requested, allowing for proper routing.
• Packet-switching When a message's packets are sent on the Internet, routers try to find the optimal route for each packet. This can result in packets being sent on different routes to their destination. After the packets arrive they are re-assembled into the original message for the recipient. For more details on packet-switching, see this interactive web page.
• Protocol A protocol is the set of rules that govern how communications take place on a network. For example, File Transfer Protocol (FTP) are the communication rules for transferring files from one host to another. TCP/IP, discussed earlier, is known as a protocol suite since it contains numerous protocols.

The 1980s witnessed a significant growth in Internet usage. Internet access came primarily from government, academic, and research organizations. Much to the surprise of the engineers, the early popularity of the Internet was driven by the use of electronic mail.

Initially, Internet use meant having to type commands, even including IP addresses, in order to access a web server. That all changed in 1990 when Tim Berners-Lee introduced his World Wide Web project which provided an easy way to navigate the Internet through the use of hypertext. The World Wide Web gained even more steam in 1993 with the release of the Mosaic browser which allowed graphics and text to be combined as a way to present information and navigate the Internet.