PDF

Portable Document Format

This is a file format developed by Adobe Systems in 1992. PDF captures formatting information from a variety of desktop publishing applications, making it possible to send formatted documents and have them appear on the recipient’s monitor or printer as they were intended. This is because a PDF will maintain the original fonts, images, graphics as well as the exact layout of the file.

Innovation

COMPUTER

SERVER

A computer. A computer that awaits and responds to requests for data.

Example: a DNS server awaits and responds to requests for urls to be translated to IP addresses

Internet

A groups of computers and servers that are connected to each other.

An ISP is your gateway to the Internet and everything else you can do online; a company that provides subscribers access to the Internet.

ISP.    Examples:Verizon, ATT, Comcast, Time Warner, Cox,

CLIENT 

A computer that requests data stored on a server.

Example: When you type an address into your browser, your computer is the client and it sends the request to the DNS server.

 web Server

1. A program that uses HTTP (Hypertext Transfer Protocol) to serve the files that form Web pages to users, in response to their request, which are forwarded by their computers’ HTTP clients.

2. Dedicated computer and appliances may be referred to as a Web servers as well.

3. Web servers are computers on the internet that deliver(store) web pages. Every web server has an IP address and possibly a domain.

File Server 

A computer and storage device dedicated in storing files. Any user on the network can store files on the server.

Proxy Server 

A server that sits between a client application, such as a web browser, and a real server. It intercepts all requests to the real server to see if it can fulfill the requests itself. If not, it forwards the request ot the real server.

Cloud Computing 

The practice of using a network of remote servers from data centers all over the worldlm  hosted on the Internet to store, manage, and process data, rather than a local server or a personal computer

Cloud server

Cloud server hosting is when hosting services are made available to customers on demand via the internet. Rather than being provided by a single server or virtual server, cloud server hosting services are provided by multiple connected servers that comprise a cloud.

Application server 

A program that handles all application operations between users and an organization’s backend business applications or databases.

Dedicated server 

A single computer in a network reserved for serving the needs of the network. For example, some networks require that one computer be set aside to manage communications between all the other computers.

Print Server 

A computer that manages one or more printers, and a network server is a computer that manages network traffic.

Database server 

A computer system that processes database queries.

Binary

A way of representing information using only two options, usually 0’s and 1’s.

Yes/No

True/False

Packets 

Small chunks of information that have been carefully formed from larger chunks of information.

Protocol

A set of rules and standards used to communicate between machines.

HTTP

HyperText Transfer Protocol - the protocol used for transmitting web pages over the internet.

HTML 

HTML HyperText Markup Language) is the language in which the content and formatting of a web page are written.

ASCII

American Standard Code for Information Interchange. ASCII is the university recognized raw text format that any computer can understand.

Net Neutrality

The principle that all Internet traffic should be treated equally by Internet Service Providers.

Bit

A contraction of “Binary Digit.” A bit is the single unit of information in a computer typically represented as 0 or

Code( Verb )

To write code, or to write instructions telling the computer what to do.

IETF

Internet Engineering Task Force - Develops and promotes voluntary Internet standards and protocols, in particular the standards that comprise the Internet protocol suite.

ISOC

the Internet Society strives to make the world a better place.

URL

Uniform Resource Locator: An easy-to-remember address for calling a web page (like www.code.org).

 Internet Protocol Stack 

DNS, TCP, IP, and Physical Internet

Code.org’s  stack

DNS 

Domain Server Name or Domain Name Service: The service that translates URLs to IP addresses.

TCP/IP 

Transmission Control Protocol - Provides reliable, ordered, and error-checked delivery of stream of packets in the internet. TCP is tightly lightly linked with IP and usually seen as TCP/IP in writing.

IP Adress 

A number assigned to any item that is connected to the Internet.

Router 

A device that forwards data packets along networks. A router is connected to at least two networks and are located at gateways.

Latency Time 

Time it takes for a bit to travel from its sender to its receiver.

Birate 

The number of bits that are conveyed or processed per unit of time.

Bandwith 

Transmission capacity measured by bit rate.

The speed of an Internet connection. A bandwidth of 5 mbps can process 5 megabytes, or 500 bytes, of digital information every second without slowing down or crashing.

Bandwidth can also be the amount of data you are allowed to send or receive in a network. Schools and businesses sometimes have bandwidth limits for their users to keep the network from slowing down.

See a sample Internet Bandwidth Guide

Bit 

A contraction of “Binary Digit.” A bit is the single unit of information in a computer, typically represented as a 0 or 1.

Byte 

A byte is a sequence of 8 bits processed as a single unit of information.

Why is a byte 8 bits? 

A byte is 8 bits since it was used to refer to groups of 8-bits that a

computer was processing.

Mbps 

megabits per second

Broadband speeds are measured in 'megabits per second', often shortened to Mb Mbits p/s or Mbps. Bits are tiny units of data, with a megabit representing a million of them. The higher the number of Mbps (megabits per second) you have, the speedier your online activity should be.

Heuristic 

A problem solving approach (algorithm) to find a satisfactory solution where finding an optimal or exact solution is impractical or impossible

Lossless Compression 

A data compression algorithm that allows the original data to be perfectly reconstructed from the compressed data.

Abstraction 

Reducing information to a simpler form, to remove some details to focus on essential characteristics. It is typically possible to look at a system at many levels of abstraction, depending on how many detail is necessary to approach the challenge at hand. To simplify things pulling out specific differences to make one solution work  for multiple problems.

File Sizes Byte,KB,MB,GB,TB 

A byte is a sequence of 8 bits (enough to represent one alphanumeric character) processed as a single unit of information. A single letter or character would use one byte of memory (8 bits), two characters would use two bytes (16 bits)

File Sizes (2) 

Put another way, a bit is either an ‘on’ or an ‘off’ which is processed by a computer processor, we represent ‘on’ as ‘1’ and ‘off’ as ‘0’. 8 bits are known as a byte, and it is bytes which are used to pass our information in its basic form - characters.

File Sizes (3) 

A byte is a sequence of 8 bits (enough to represent one alphanumeric character) processed as a single unit of information. A single letter or character would use one byte of memory (8 bits), two characters would use two bytes (16 bits).

Internet Protocol Layers 

DNS: Translates a URL into an IP address. Note that a DNS request still is conducted over TCP/IP

TCP: Breaks larger messages into multiple packets and ensures all packets are received and ordered correctly

IP: Assigns IP addresses to computers and routes packets of data to the correct address

The Physical Internet: copper wire, fiber, optic cable, radio waves, etc

Server 

A computer that awaits and responds to requests for data. Example: a DNS server awaits and responds to requests for urls to be translated to IP addresses.

Client 

A computer that requests data stored on a server. Example: When you type an address into your browser, your computer is the client and it sends the requests to the DNS server.

Client 

A computer that requests data stored on a server. Example: When you type an address into your browser, your computer is the client and it sends the requests to the DNS server.

Lossy Compression 

To save space, some information is thrown away

Resolution 

The dimensions by which you can measure how many pixels are on a screen.

640 x 480

Metadata 

Data the describs data. For example, a digital image may include metadata that describes the size of the image, number of colors, or resolution.

Pixel 

Short for “picture element” it is the fundamental unit of a digital image, typically a tiny square or dot which contains a single point of color of a larger image.

Hexadecimal Number 

A number system consisting of 16 distinct symbols - 0-9 and A-F - which can occur in each place value.

Favicon 

Short for Favorite Icon

RGB 

The RGB color model uses varying intensities of (R)ed, (G)reen, and (B)lue light are added together in to reproduce a broad array of colors

Aggregation 

A computation in which rows from a data set are grouped together and used to compute a single value of more significant meaning or measurement. Common aggregations include: Average, Sum, Max, Min, Count. A Summary Table, Calculation Area

Lossy Compression 

(or irreversible compression) a data compression method that uses inexact approximations, discarding some data to represent the content. Most commonly seen in image formats like .jpg

Pivot Table 

In spreadsheet software, it is the name of the tool used to create summary tables.

Summary Table 

A table that shows the results of aggregations performed data from a larger data set

Boolean

A single value of either TRUE or FALSE

Boolean Expression 

In programming, an expression that evaluates to TRUE or FALSE

Computationally Hard 

A “hard” problem for a computer is one in which it cannot arrive at a solution in a reasonable amount of time

Javascript 

A programming language designed by Sun Microsystems that can be integrated into standard HTML pages to add some dynamic features.  

    Learn more here.

Event Handling 

An  overarching term for the coding tasks involved in making a program respond to events by triggering functions.

Ul Elements 

On-screen objects, like buttons, images, text boxes, pull down menus, radio buttons, check boxes,  screens,canvas, and so on.Input Controls: checkboxes, radio buttons, dropdown lists, list boxes,buttons, toggles, text fields, date field.

Expression 

Any valid unit of code that resolves to a value.

Debugging 

Finding and fixing problems in your algorithm or program.