BJC Unit 4 Vocab

• internet

• a computer network that uses open protocols to standardize communication. a computing device connected to an internet-computing device is required to access the internet

• computer network

• an interconnected computer system that is capable of sending data

• computer system

• a group of computing devices and services working together for a common purpose

• computing device

• a physical object that can run a program, like computers, phones, and smart sensors

• The World Wide Web

• a system of linked pages, programs, and files that use the Internet

router

a computer that passes information from one network to another

ISPs

(Internet Service Providers) are the companies who sell Internet access to homes and institutions.

Bandwidth

the maximum amount of data that can be sent in a fixed amount of time (for digital data, it is measured in bits per second). Higher bandwidth is better because the data will travel more quickly.

Storing data in the cloud

storing it somewhere on the Internet, but you don't know where. The cloud service provider (Google, Dropbox, Amazon, Snap!, etc.) manages the actual storage location

path

a sequence of directly connected computing devices that connect a sender to a receiver

Routing

the process of finding a path from sender to receiver

Scalability

the ability of the Internet to keep working as it grows

Redundancy

the inclusion of back-up elements in case one part fails

Fault tolerance

the ability of a system to work around problems

protocol

set of rules that specify the behavior of a system

IP address

a unique number assigned to each device on a computer network

packet

a small chunk of any kind of data (text, numbers, lists, etc.) and metadata (information about the data) that is passed through the Internet as a data stream

Packet switching

Internet sends short bursts of information, not long continuous strings

IP

Internet Protocol) lets your computer pretend it has a direct connection to another computer. The routers at every connection point on the Internet run IP, which transmits packets from one IP address to another

TCP

Transmission Control Protocol) lets your computer pretend it has a reliable connection to the other computer. The computers (including servers) at the two endpoints of a communication run TCP, which guarantees that packets arrive successfully.

Encryption

the process of encoding data to prevent unauthorized access

Decryption

the process of decoding the data

symmetric encryption

use the same key for both encryption and decryption; ex: Substitution ciphers

Public key encryption

uses a pair of keys: a public key for encryption and a private key for decryption. The sender uses the public key to encrypt the message, and receiver uses their private key to decrypt it.

SSL/TLS

(secure sockets layer/transport layer security) is the standard used for cryptographically secured information transfer on the Internet.

Certificate authorities

organizations that issue digital certificates to verify who owns the encryption keys used for secured communications.

Instead of trusting that the website is who they say they are, you now have to trust that the Certificate Authority is reliable.

Malware

software that was designed to harm or take partial control over your computer.

Keylogging software

a kind of malware that records every key pressed by a user

computer virus

malware that spreads and infects other computers. Viruses can attach themselves to legitimate programs

Antivirus or anti-malware software

software designed to scan your files and Internet transmissions looking for malware

firewall

a security system that controls the kinds of connections that can be made between a computer or network and the outside world.

Phishing

a common security attack in which the victim is tricked into giving up personal information or downloading malware

DDoS (Distributed Denial of Service) attack

uses a virus to flood a server with many requests from many computers at once so that users of that server are denied service.

rogue access point

a wireless access point that gives access to a secure network without the authorization of the network administrator

digital divide

unequal access to computers and the Internet based on poverty, racism, sexism, isolation in the countryside, age, and other factors. The digital divide affects both individuals within a country and countries themselves.

Citizen science

scientific research conducted in whole or part by distributed individuals, many of whom may not be scientists, who contribute relevant data to research using their own computing devices.

Crowdsourcing

the general term for using the Internet to get a lot of people to help solve a problem. (Citizen science is a type of crowdsourcing.)

computing innovation

physical (such as a self-driving car), non-physical software (such as picture editing software), or conceptual (such as the idea of e-commerce), but regardless of the form, they must include a program as an integral part of their function.

bit

a single unit of data that can only have one of two values. We usually represent the two values as 0 (off) and 1 (on).

byte

eight bits

word

a sequence of however many bits the CPU processes at a time. As of 2017, words are 32 or 64 bits

binary sequence

a string of ones and zeros.

Analog data

have values that change smoothly, unlike digital data which change in discrete intervals.

Sampling

measuring values, called samples, of an analog signal at regular intervals.

sampling rate

the number of samples measured per second.

width

the number of bits that a CPU processes at a time

word

a binary sequence of that many bits

Floating point

Scientific notation (such as 2,350,000 = 2.35 × 10⁶) uses powers of ten to represent very large or very small values. Floating point is the same idea but with powers of two.

The word "bit" is an abbreviation for

binary digit.

Lossless data compression algorithms

(such as PNG) are reversible (there is no loss in quality); you can reconstruct the original data.

Lossy data compression algorithms

are not fully reversible; you can reconstruct only an approximation of the original data.