ICT 141 Computing Skills Fundamentals I Lecture 3 - Introduction to Internet & Email PDF

ICT 141 COMPUTING SKILLS FUNDAMENTALS I FACULTY OF SCIENCE Lecture 3: Introduction to Internet & Email Computing Skills Fundamentals 1 The Internet  The Internet (the “Net” or “net”) is a worldwide computer network that connects hundreds of thousands...

ICT 141 COMPUTING SKILLS FUNDAMENTALS I FACULTY OF SCIENCE Lecture 3: Introduction to Internet & Email Computing Skills Fundamentals 1 The Internet  The Internet (the “Net” or “net”) is a worldwide computer network that connects hundreds of thousands of smaller networks. These networks link educational, commercial, non-profit, and military entities, as well as individuals.  A global system of interconnected computer networks that use the standard Internet Protocol suite (TCP/IP) to link several billion devices worldwide.  An international network of networks consisting of millions of private, public, academic, business, and government networks, linked by a broad array of electronic, wireless, and optical networking technologies.  AKA The Net, Info. Superhighway, Cyberspace. 2 Internet penetration ICT121 – 2015/16 3 Who owns the Internet?  No one owns the Internet, and no single person or organization controls the Internet in its entirety  The Internet is more of a concept than an actual tangible entity  It relies on a physical infrastructure that connects networks to other networks  History of the Internet begins with the development of electronic computers in the 1950s 4 How the internet work The Internet is basically a huge network that connects hundreds of thousands of smaller networks. Central to this arrangement are client/server networks – Client: computer requesting data or services – Server or host computer: central computer supplying data or services requested of it Client 5 Connecting to the internet To connect to the Internet you need 1. An access device (computer with modem) 2. A means of connection (phone line, cable hookup, or wireless) 3. An Internet access provider Connecting to the internet However you connect to the Internet, the bandwidth will determine the speed of your connection. Bandwidth: Expresses how much data can be sent through a communications channel in a given amount of time. Baseband: Slow type of connection that allows only one signal to be transmitted at a time. Broadband: High-speed connections (Several signals can be transmitted at once) 7  Data Transmission Speeds – Originally measured in bits per second (bps) – 8 bits are needed to send one character, such as A or a – Kbps connections send 1 thousand bits per second – Mbps connections send 1 million bits per second – Gbps connections send 1 billion bits per second – Uploading & Downloading Upload—transmit data from local to remote computer Download—transmit data from remote to local computer Intranet vs. Extranet  Intranets—use infrastructure and standards of the Internet and the web, but for an organization’s internal use only.  Extranets—similar to intranets but allows use by selected outside entities, such as suppliers. 9 Internet services and Uses  Email And Discussion groups  Research & Information  News  Entertainment  File Downloading  E-Shopping  Financial matters  Online Auctions  Career advancement  E-Business  Social Networking 10 World WideWeb (WWW) ?  Def: The web and the Internet are not the same; the web is multimedia-based, and the Internet is not. The Internet is the infrastructure that supports the web. The World Wide Web (the “Web” or the “web” is an interconnected system of Internet computers (called servers ) that support specially formatted documents in multimedia form. An information-sharing model built on top of the Internet, hence a way of accessing information over the medium of the Internet. A system of interlinked hypertext documents that are accessed via the Internet 11 Useful concepts  Hypertext: text displayed on a monitor or with references (hyperlinks) to other text which the reader can immediately access  Hyperlink: a reference to data that the reader can directly follow either by clicking or by hovering or that is followed automatically  Hypertext Markup Language (HTML): An authoring language used to create documents on the World Wide Web. 12 Web Browser  Commonly referred to as a Browser  A software application for retrieving, presenting and traversing information resources on the World Wide Web.  An information resource is identified by a Uniform Resource Locator (URL) ◦ E.g: web page, image, video or other piece of content. 13 Web Browser Cont…  Uses a client-server model ◦ Browser: client running on a computer that contacts the Web server and requests for information, ◦ Web server: sits somewhere on the internet  sends the information back to the Web browser which displays the results on the computer or other Internet-enabled device that supports a browser. 14 Examples of web browsers  The two most popular browsers: Microsoft Internet Explorer and Mozilla Firefox,  Other major browsers include Google Chrome, Apple Safari and Opera,  While most commonly use to access information on the web, a browser can also be used to access information hosted on Web servers in private networks such as INTRANETS. 15 Mobile browsers  Also referred to as a microbrowsers  Designed for web access through mobile devices  Mobile browsers are ◦ typically "stripped down" versions of everyday Web browsers and offer fewer features in order to run well on mobile devices. ◦ optimized to display web content on smaller mobile device screens which have far less computing power and memory capacity as desktop or laptop. 16 Webpages vs.Websites  Webpage: A document commonly written in HyperText Markup Language (HTML) that is accessible through the internet or other network using a browser.  Website: A collection of one or more web pages grouped under the same domain name.  A domain name is your website name. A domain name is the address where internet users can access your website. For example, www.ActNowDomains.com is this web site's domain name.  Web pages and websites are accessed by entering a Uniform Resource Locator (URL) addresses 17 URL  URL: A global address of documents and other resources on the World Wide Web  Consist of three parts ◦ Network protocol (protocol identifier: what protocol to use) ◦ Host name or address (the domain name where the resource is located) ◦ File or resource location (www resource)  These substrings are separated by special characters as follows: ◦ protocol :// host / location  Typical URL protocols include http://, ftp://, and mailto:// 18 Examples  http://www.ietf.org/rfc/rfc2396.txt  http://searchnetworking.techtarget.com/WhatIs/images/ coaxla.gif  ftp://www.somecompany.com/whitepapers/widgets.ps ICT121 – 2015/16 15 Static webpages  Delivered exactly as stored  Displays the same info for all users, at all times .html files  Easily created (no programming skills)  No need for web server  E.g. a student’s personal profile page 20 Dynamic webpages  Prepared with fresh content or layout for each viewing. Customizes itself frequently and automatically, based on certain criteria.  Dynamic web pages are used where the information is changed frequently, for example, stock prices, weather information, etc.  Changes with time, user, user interaction, context  Client-Side scripting ◦ e.g. JavaScript (presentation)  Server-Side scripting ◦ e.g. ASP (Active Server Pages), PHP (PHP HyperText Processor)  E.g. online store: different prices, reviews, user information 21 HyperText Transfer Protocol  HTTP: is a protocol used for viewing webpages on the web. It is the foundation of data communication for the World Wide Web.  File Transfer Protocol (FTP): A network protocol used to transfer computer files from one host to another host over a TCP-based network, such as the Internet. ◦ FTP is built on a client-server architecture 22 Internet Security Protocols  HTTPS: In standard http all information is sent in clear text. HTTP with a security feature. Encrypts the data that is being retrieved by the HTTP.  Secure socket layer (SSL): a standard security protocol for establishing an encrypted link between a server and a client. Sensitive data such as credit card numbers, social security numbers, and login credentials can be transmitted securely  Transport Layer Security: latest industry standard cryptographic protocol. The successor to SSL  Advanced Encryption Standard (AES): an encryption algorithm for securing sensitive data over the internet 23 FIREWALL  FIREWALL: A system designed to prevent unauthorized access to or from a private network.  Firewalls are frequently used to prevent unauthorized internet users from accessing private networks connected to the internet e.g. intranets.  All messages entering or leaving the intranet pass through the firewall for examining  Firewall blocks those messages that do not meet the specified network security criteria 24 Search engines  Systems or websites designed to search for information on the World Wide Web  Several engines out there (next slide)  Search results are normally presented as a list of results ◦ Often referred to as search engine results pages 25 Examples of search engines 26 Email services  Electronic mail, most commonly referred to as email or e-mail  First email sent in 1971 by Ray Tomlinson to himself ICT121 – 2015/16 27 Email addresses  Gmail.com  Yahoo.com  Hotmail.com  MySpace.com  Fastmail.com  Mail.com  Fanbox.com 28 Composing an email  TO: List of addresses/everyone you sending message to  Carbon Copy (CC): List of addresses/everyone you copying the message to. They can see original recipients and also visible to intended recipients  Blind Carbon Copy (BCC): List of addresses/everyone blind copied on the email message. The cannot see other recipients and also not visible to intended recipients  SUBJECT: Message title display 29 Email parts ICT121 – 2015/16 30  Email Attachments – A copy of a file or document that you send attached to an email to one or more people – Recipients must have compatible software to open the attachment; for example, if they don’t have Excel, they probably can’t read the spreadsheet you sent them. – Be careful about opening attachments: Many viruses hide in them; scan them with antivirus software Know who has sent the attachment before you open it Challenges of Using the internet  Privacy Issues  Security issues  There is no central governing body  Some unauthorized websites 32 Computing Skills Fundamentals 33