Comp Sci: computer basics, world wide web

Hardware

physical components of a computer system

(ex - monitor, mouse, hard drive)

software

the programs that execute on the computer

(ex word processing program, web browser)

von nueman architecture

memory → central processing unit (CPU) → input output devices (I/O)

memory

stores programs/ data and allows programs to be processed (memory stored by bits

Central Processing Unit

(brains of the computer) made of circuitry and carries out the instructions to process information

Input/output (I/O)

input allows computers to receive data and instructions while output allows the computer to display or broadcast its results.

bits (apart of memory)

are the building block of digital memory, and the grouping makes larger values represented

bit = 2 values etc (2^N = values)

bytes (apart of memory)

1 byte = 8 bits (large collections represented

kilobyte (2^10)

a kilobyte can store a few paragraphs (roughly 1 thousand characters)

megabyte (2 ^ 20)

store a book (roughly a million characters)

gigabyte (2 ^ 30)

can store a small library (roughly a billion characters)

terabyte (2 ^40)

can store a book repository (roughly 1 trillion characters)

operating systems

is a collection of programs that controls how the CPU, memory, and I/O devices work together (kernals, file systems, graphic user interface)

World wide web 1990

software and consists of web pages, images, sound files etc)

internet (1969)

hardware and consists of computers around the world and the communication that links them.

tim berners lee

created the World Wide Web (1990), founded world wide web consortium, and was knighted by queen elizabeth)

World Wide Web consortium

main international standards organization for the World Wide Web. Founded in 1994 and led by Tim Berners-Lee, the consortium is made up of member organizations that maintain full-time staff working together in the development of standards for the World Wide Web

web growth

how people built off it, like the first browser (internet explorer) then google

web page

text document that contains additional formatting information in a language called HTML (HyperText Markup Language)

web browser

is a program that accesses a Web page, interprets its content, and displays the page

web server

is an Internet-enabled computer that executes software for providing access to certain Web document

it stores pages and files (images, videos, …) and sends them to browsers who request them

web addresses

Web pages require uniform names to locate and identify them uniquely

neach page is assigned a Uniform Resource Locator (URL) different parts of the Web address provide information for locating the page

search engines (1990s)

(as web grew it bec ame difficult to find resources) the Google search engine began in 1996 as a research project by Stanford grad students Larry Page and Sergey Brin

HTML (hyptertext markup language)

utilizes tags to markup page content, these tags tell the browser how to display the contents, HTML5 is the current standard, supported by all browsers

HTTP (hypertext transfer protocol)

defines how messages between browsers and servers are formatted, the prefix http:// in a URL specifies that the HTTP protocol is to be used in communicating with the server, the prefix https:// is similarly used for secure communications

caching (efficiancy)

when a webpage is first downloaded, it is temporarily stored on the computer, the next time the page is requested, the browser checks if the copy is already there.

cookies (loophole)

small file that can be stored and accessed by a Web server, when the user visits a site, the Web server is allowed to store a small amount of data in a cookie file (e.g., date & time of visit, items purchased)