CIS 300
Chapter 1 – Internet and Web Basics
• Internet: interconnected network of computer networks
o Began as a network to connect computers at research facilities and universities
o National Science Foundation’s NSFnet created and connected with ARPAnet
o Ban on commercial use of internet was lifted in 1991
• Berners-Lee created the World Wide Web
o Hypertext Transfer Protocol (HTTP)
o Hypertext Markup Language (HTML)
o Mosaic – first graphical web browser
• W3C Recommendations
o Developing recommendations and prototype technologies related to the Web
• Web Standards and Accessibility
o Web Accessibility Initiative (WAI)
• Network Overview
o Network: two or more computers connected for the purpose of communicating
and sharing responses
o Clients: computer workstations used by individuals
o Server: receives requests from client computers for resources
o Media: connecting the clients, servers, peripherals, and networking devices may
consist of copper cables, fiber optic cables, or wireless technologies
• Client/Server Model
o Term from 1980s
o Web client
▪ Connected to the internet when needed
▪ Usually runs web browser (client) software such as Internet Explorer or
Firefox
▪ Uses HTTP
▪ Requests web pages from a web server
▪ Receives web pages and associated files from a web server
o Web server
▪ Continually connected to the Internet
▪ Runs web server software (such as Apache or Microsoft Internet
Information Server)
▪ Uses HTTP
▪ Receives a request for a web page
▪ Responds to the request and transmits the status code, web page, and
associated files
• Multi-purpose internet mail extensions (MIME)
o Rules that allow multimedia documents to be exchanged among many different
computer systems
o Provides for the exchange of seven different media types on the internet: audio,
video, image, application, message, multipart, and text
• Email protocols
o Simple Mail Transfer Protocol (SMTP)
▪ When you send an email to others
o Post Office Protocol and Internet Message Access Protocol
▪ When you receive email
• Hypertext Transfer Protocol
o HTTP is a set of rules for exchanging files such as text, graphic images, sound,
video, and other multimedia files on the web
o Used by web browsers to request web pages and their associated files to display
a web page
• File Transfer Protocol (FTP)
o Set of rules that allow files to be exchanged between computers
o Used to move files from one computer to another
• Transmission Control Protocol/Internet Protocol
o TCP/IP has been adopted as the official communication protocol of the internet
o TCP: purpose of TCP is to ensure the integrity of network communication
o Starts by breaking files and messages into individual units called packets
o Packets contain info such as destination, source, sequence number, and
checksum values used to verify the integrity of the data
o TCP is used with IP to transmit files efficiently over the internet
• IP
o Set of rules that controls how data are sent between computers on Internet
o IP routes a packet to the correct destination address
o Once sent, packet gets successively forwarded to the next closest router
• IP Addresses
o Each device connected to the internet has a unique IP address
o IPs consist of a set of four groups of numbers, called octets
• Domain Name System (DNS)
o Associates these IP addresses with the text-based URLs and domain names
• URIs and URLs
o Uniform Resource Identifier (URI) identifies resource on internet
o Uniform Resource Locator (URL) is type of URI that represents the network
location of a resource such as a web page, graphic file, MP3 file
• Domain Names
o Domain name: locates an organization or other entity on the internet
• Domain Name System (DNS) divides the internet into logical groups and understandable
names by identifying the exact address and type of organization
• Subdomain: can be configured to house a separate website located at the same domain
• Top level domain names
o TLD identifies the rightmost part of the domain name
o Either a generic top-level domain (gTLD) such as com for commercial, or a
country-code top-level domain such as fr for France
• Generic Top-Level Domain Names (gTLDs)
• Domain Name Systems (DNS)
o DNS associates domain names with IP addresses.
o Each time a new URL is typed into a web browser
▪ DNS is accessed
▪ The corresponding IP address is obtained and returned to the web
browser
▪ The web browser sends an HTTP request to the destination computer
with the corresponding IP address
▪ The HTTP request is received by the web server
▪ The necessary files are located and sent by HTTP responses to the web
browser
▪ The web browser renders and displays the web page and associated files
• Markup languages
o Consist of sets of directions that tell the browser software how to display and
manage a web document
o Usually called tags and perform functions such as displaying graphics, formatting
text, and referencing hyperlinks
• HTML
o Set of markup symbols or codes placed in a file that is intended for display on a
web page
o Identify structural elements such as paragraphs, headings, and lists
o Can also be used to place media on a web page and describe fill-in forms
• XML
o XML is extensible Markup Language
o Developed by W3C to create common information formats and share the format
and the information on the web
o Text-based syntax designed to describe, deliver, and exchange structured
information such as RSS feeds
• XHTML
o Extensible HyperText Markup Language uses the tags and attributes of HTML4
along with the more rigorous syntax of XML
• HTML5 – Newest version of HTML
o New way to code
• Document Type Definition (DTD)
o DTD identifies the version of HTML contained in the document
o Browsers and HTML code validators use the info in the DTD when processing the
web page
• Web Page Template always starts the same
• HTML Element
o Purpose is to indicate that the document is HTML formatted
o The opening <html> tag is placed on a line below the DTD
o The closing </html> tag indicates the end of the web page and is placed after all
the other HTML elements in the document
• Lang attribute specifies the spoken language of the document
o Lang=”en”
• Head section
o Contains information that describes the web page document
o Head element
▪ Contains the head section, which begins with the <head> tag
o Title element
▪ Configures the text that will appear in the title bar of the browser
window. <title>
o Meta element
▪ Describes a characteristic of a web page, such as the character encoding
▪ Character encoding: internal representation of letters, numbers, and
symbols in file
▪ Charset attribute: indicates character encoding
• Body section
o Contains actual tags, text, images, and other objects that are displayed by
browser as web page
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