The Internet Presented by Frank H. Osborne, Ph. D. © 2005 Bio 2900 Computer Applications in Biology

The Internet The Internet is a modern means of electronic communication. The Internet began as a way to permit rapid communication between the Defense Department and university research sites in the 1950s and 1960s. The basic Internet functions within the UNIX operating environment.

Elements of the Internet permits sending electronic messages in text form anywhere in the world. The World Wide Web is a collection of sites and pages in graphic form which can be viewed using a browser. There are other elements such as newsgroups and chat rooms.

Vision of the Internet In the 20 th century, communication was done with text. At the beginning of the computer age it was envisioned that text would be sent electronically, in a form called hypertext.

TCP/IP TCP/IP means Transmission Control Protocol/Internet Protocol. A protocol is a set of rules that are used to transmit information on the Internet. There are several such services: –http: hypertext transmission protocol –ftp: file transmission protocol –gopher: a means of exploring the non- graphic Internet for information.

TCP/IP TCP/IP sends information in small electronic parcels called packets. Packets are sent through the Internet using routers, which are used to make sure each packet arrives at the correct destination. To connect various networks to the Internet, a gateway computer is used.

Internet Addressing—The URL The URL is the Universal Resource Locator or Internet address for a particular location on the Internet. The URL was developed at CERN (European Organisation for Nuclear Research) which created the technological basis for the World Wide Web.

Internet Addressing—The URL IP address –The IP address consists of four sets of numbers punctuated by dots. –Example: is the address for the Kean University web server also known as turbo. –The turbo server contains the Kean Website. –In this example the part refers to Kean while the remaining numbers reference individual servers.

Internet Addressing—The URL The URL is a unique descriptor that can identify any document, graphic, computer or other item anywhere on the Internet. URLs are like business cards for locations on the Internet. A browser generally has a place near the top of the window where which the current URL is placed.

Reading a URL (1) Parts of a URL service: // hostname / directory-path Service: will be http: or ftp:. // - a UNIX separator indicating that the location is on a different computer hostname is the name of the host computer where the file you seek is to be found. / is the UNIX separator for directories (compared with DOS which is \) directory-path tells the route to the file

Reading a URL (2) URL for Dr. Osborne's Bio 2900 Website indicates hypertext transmission protocol –www – indicates the server or location of the file –kean – is the domain name of the host computer –edu – is the zone that indicates an academic site

Reading a URL (3) URL for Dr. Osborne's Bio 2900 Website ~fosborne/B2900/ – is the directory path. A directory is like a drawer in a file cabinet. It may contain other drawers, or it may contain files. ~fosborne –is the main directory assigned to Dr. Osborne B2900 is a directory within the main directory. It contains files for Bio 2900

Reading a URL (4) URL for Dr. Osborne's Bio 2900 Website B2900_home_page.htm is the name of a particular file. A browser will display the entire pathname as shown above. The name of the particular file you are viewing is found all the way to the right. HTML internet files generally end in.html or.htm

URL Rules (1) Spaces are not allowed in a URL. A filename with a space will cause the following effect: (%20) (In ASCII the space character is 32 in base 10—the equivalent of 20 in hexadecimal.) Spaces are permitted in file names but a browser will fill each space with %20.

URL Rules (2) You may have a file in your directory called my best file.htm If you look at it with a browser the browser will show its filename as my%20best%20file.htm Two ways around this problem are: –MyBestFile.htm –my_best_file.htm (note that the "_" is the underscore character)

How the Internet finds things You type the complete pathname of a location into your browser. A DNS (Domain Name System) Server will translate the domain name into an IP address for the item.

Top level domain name zones.com - commercial sites or corporations.edu - educational organizations.gov - governmental websites.mil - military sites.net - network administration.org - other types of organizations Newly added categories for various uses.biz,.name,.info

Country codes for some non-US websites.au - Australia.ca - Canada.de - Germany.jp - Japan.tv - Tuvalu.uk - United Kingdom

Standard Form for State Websites The standard form for any state website is: in which xx is the two- letter abbreviation for the state. For example, the New Jersey State Website is found at:

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