Technology Glossary: Terms for Then-and-Now Comparisons

A

Analog signal: A signal that varies continuously, like the groove on a record or the voltage from a microphone, so that its shape mirrors the original sound or image. It can capture fine detail but picks up noise easily and degrades when copied. See: Vinyl Records vs Music Streaming · Cassette Tapes vs Digital Audio · Broadcast Radio vs Podcasts

B

Bandwidth: The amount of data a connection can carry in a given time. Higher bandwidth lets more information pass at once, which matters for large files and video, though it does not by itself determine how quickly a single message arrives. See: Dial-Up Internet vs Fiber Connections · VHS Tapes vs Video Streaming
Barcode: A pattern of parallel lines of varying widths that a scanner reads with reflected light to identify a product or item. It usually holds only an identifying number, which a computer then matches to a record. See: Mechanical Cash Registers vs Point-of-Sale Systems · Paper Tickets vs Mobile Passes

C

Carburetor: A device that mixes air and liquid fuel in proportions suited to an engine, using the flow of air to draw fuel through small passages. It works mechanically, without sensors or electronic control. See: Carburetors vs Fuel Injection
Cathode ray tube: A sealed glass tube in which an electron beam is steered onto a phosphor-coated screen to make it glow. It was the basis of most television sets and computer monitors for decades before flat panels replaced it. See: CRT Televisions vs Flat-Panel Displays
Chronometer: A precise portable timekeeper, originally developed for finding longitude at sea. Because position east or west depends on knowing the time at a reference place, an accurate clock made navigation far more reliable. See: Sextants vs Satellite Positioning · Analog Clocks vs Smartwatches
Circuit switching: A way of connecting calls by reserving a dedicated path between two parties for the whole conversation. Traditional telephone exchanges worked this way, unlike networks that break messages into shared packets. See: Telephone Exchanges vs Internet Calling · Rotary Phones vs Smartphones
Cloud storage: Data kept on remote computers run by a service and reached over the internet, rather than on a device you hold. It allows access from many places, but depends on the provider, an account, and a working connection. See: Floppy Disks vs Cloud Storage · Photo Albums vs Cloud Photo Libraries
Compression: Techniques that make data take less space or travel faster by removing redundancy or details people are unlikely to notice. Some methods can be reversed exactly; others discard information permanently in exchange for smaller files. See: Cassette Tapes vs Digital Audio · VHS Tapes vs Video Streaming · Film Cameras vs Digital Cameras
Computer-aided design: Software used to create and modify technical drawings and models on a computer. Designs can be edited, copied, measured, and shared without redrawing, which changed how engineers, architects, and manufacturers prepare their work. See: Manual Drafting vs Computer-Aided Design

D

Dial pulse: The signaling method of rotary telephones, in which a rotating dial briefly interrupts the line's electrical current a number of times matching each digit. Exchange equipment counted those interruptions to route the call. See: Rotary Phones vs Smartphones · Telephone Exchanges vs Internet Calling
Dial-up connection: An internet connection made by using a modem to place an ordinary telephone call to a provider. It shared the phone line with voice calls and carried data far more slowly than later broadband technologies. See: Dial-Up Internet vs Fiber Connections
Digital signal: A signal represented as a series of separate values, most often bits, rather than a continuously varying quantity. Digital data can be copied and transmitted without gradual loss, provided errors are detected and corrected. See: Cassette Tapes vs Digital Audio · Fax Machines vs Digital Document Sharing · Vinyl Records vs Music Streaming

E

EEPROM: A type of memory chip that keeps its contents without power and can be erased and rewritten electrically. It was an important step toward flash memory, which stores data by trapping electric charge in tiny cells. See: Punch Cards vs Solid-State Storage · Floppy Disks vs Cloud Storage

F

Filament: A thin wire, traditionally of tungsten, that glows when electric current heats it. In an incandescent bulb the filament produces light, but most of the energy it uses is given off as heat. See: Incandescent Bulbs vs LEDs
Flash memory: A form of solid-state storage that holds data by trapping electric charge in cells, so it is retained without power. It has no moving parts and is used in phones, memory cards, and many drives. See: Punch Cards vs Solid-State Storage · Floppy Disks vs Cloud Storage
Fuel injection: A system that sprays a measured amount of fuel into an engine's intake or cylinders, usually under electronic control. It can adjust to conditions more precisely than a carburetor, which relies on mechanical airflow. See: Carburetors vs Fuel Injection

G

Global Positioning System: A satellite-based navigation system that lets a receiver work out its position from signals sent by orbiting satellites. It was developed by the United States government and is one of several satellite positioning systems. See: Printed Maps vs GPS Navigation · Sextants vs Satellite Positioning

I

Integrated circuit: A set of transistors and connections formed together on a single piece of semiconductor material. Putting many components on one chip made electronics smaller, cheaper to produce, and more dependable than wiring separate parts. See: Vacuum Tubes vs Transistors · Abacuses vs Electronic Calculators

L

Latency: The delay between an action and its result, such as the time a message takes to arrive or a video takes to respond. Low latency matters for conversation and games, even when overall data capacity is large. See: Telephone Exchanges vs Internet Calling · Telegraphs vs Instant Messaging
LED: A light-emitting diode, a semiconductor device that produces light when current passes through it. Unlike a filament, it does not glow from heat, which is why it generally wastes less energy as warmth. See: Incandescent Bulbs vs LEDs · CRT Televisions vs Flat-Panel Displays
Letterpress: A printing method in which raised, inked surfaces, usually metal type, are pressed against paper. Made practical in Europe with movable type, it remained a main way of printing books and newspapers for centuries. See: Printing Presses vs Digital Publishing Platforms · Printed Encyclopedias vs Digital Knowledge Platforms
Lithography: A printing process based on the fact that oil and water repel each other. An image is drawn or transferred onto a flat surface, which then accepts ink only where the image is, and prints it onto paper. See: Printing Presses vs Digital Publishing Platforms
Longitude: The east-west position of a place on Earth, measured as an angle from a chosen reference line. Determining it at sea was hard because it depends on knowing time accurately, not just the height of the sun or stars. See: Sextants vs Satellite Positioning · Printed Maps vs GPS Navigation

M

Magnetic tape: A thin plastic ribbon coated with magnetizable particles that record sound, video, or data as patterns of magnetism. It is read by passing it past a head, so access is sequential rather than instant. See: Cassette Tapes vs Digital Audio · VHS Tapes vs Video Streaming
Magnetometer: A sensor that measures the strength and direction of a magnetic field. Phones use tiny ones to sense the direction of Earth's field, which lets them act as compasses, though nearby metal and electronics can disturb the reading. See: Magnetic Compasses vs Smartphone Navigation Sensors
Modem: A device that converts digital data into signals suited to a communication line, such as a telephone line, and converts them back at the other end. The name combines the words modulator and demodulator. See: Dial-Up Internet vs Fiber Connections · Fax Machines vs Digital Document Sharing
Movable type: Individual reusable characters, usually cast in metal, that can be arranged into lines of text, printed, and then rearranged for a new page. Its adoption in Europe made printing books far faster than copying by hand. See: Printing Presses vs Digital Publishing Platforms · Printed Encyclopedias vs Digital Knowledge Platforms

N

Near-field communication: A short-range wireless technology that lets two devices exchange small amounts of data when held very close together. It is used for contactless payment and for passes stored on phones. See: Paper Tickets vs Mobile Passes · Traditional Keys vs Smart Locks

P

Packet switching: A method of sending data by breaking it into small pieces, called packets, that travel separately across a shared network and are reassembled at their destination. It underlies the internet and internet calling. See: Telephone Exchanges vs Internet Calling · Dial-Up Internet vs Fiber Connections · Telegraphs vs Instant Messaging
PID control: A feedback method that adjusts an output, such as heating, by looking at the present error, its recent history, and how quickly it is changing. It helps a system settle at a target without overshooting. See: Analog Thermostats vs Smart Thermostats
Podcast feed: A web address that publishes a list of episodes in a standard format called RSS. Listening apps check the feed regularly and fetch new episodes automatically, so anyone can publish without needing a broadcaster. See: Broadcast Radio vs Podcasts

Q

QR code: A square pattern of black and white modules that a camera can read, storing text or a web address. Unlike a simple barcode it holds data in two dimensions, so it can carry much more information. See: Paper Tickets vs Mobile Passes · Paper Timetables vs Real-Time Transit Apps

R

Radio frequency identification: A technology in which a small tag responds to a nearby reader using radio waves, identifying itself without contact or a direct line of sight. It is used in electronic toll collection, access cards, and inventory tracking. See: Toll Booths vs Electronic Toll Collection · Traditional Keys vs Smart Locks

S

Semiconductor: A material, such as silicon, whose ability to conduct electricity can be controlled. It is the basis of transistors, integrated circuits, and LEDs, and therefore of nearly all modern electronics. See: Vacuum Tubes vs Transistors · Incandescent Bulbs vs LEDs
Sextant: A handheld instrument that measures the angle between the horizon and a celestial body, such as the sun. Navigators use that angle, along with the time, to calculate their position at sea. See: Sextants vs Satellite Positioning
Solid-state: Describes electronic devices that work through the behavior of solid materials, usually semiconductors, rather than moving parts or vacuum tubes. Solid-state storage, for instance, has no spinning disk or reading head. See: Vacuum Tubes vs Transistors · Punch Cards vs Solid-State Storage
Spreadsheet: A program that arranges numbers and text in a grid of cells and recalculates results automatically when a value changes. It replaced repeated manual arithmetic with formulas that can be changed and reused. See: Mechanical Calculators vs Spreadsheets
Streaming: Delivering audio or video over a network so it can be played while it arrives, rather than after a full download. The viewer or listener accesses the content on demand without keeping a permanent copy. See: Vinyl Records vs Music Streaming · VHS Tapes vs Video Streaming · Physical Game Media vs Digital Game Distribution

T

Thermionic emission: The release of electrons from a heated metal surface. It is the effect that makes vacuum tubes work, since a hot element boils off electrons that can then be steered by other electrodes. See: Vacuum Tubes vs Transistors · CRT Televisions vs Flat-Panel Displays
Thermostat: A device that senses temperature and switches heating or cooling on or off to keep a space near a chosen setting. Older versions used a bimetallic strip that bends as it warms; newer ones use electronic sensors. See: Analog Thermostats vs Smart Thermostats
Transistor: A small semiconductor device that can switch or amplify electrical signals. It performs many of the jobs vacuum tubes once did while being smaller, cooler, and more durable, and it is the building block of modern chips. See: Vacuum Tubes vs Transistors · Abacuses vs Electronic Calculators
Trilateration: Finding a position by measuring its distance from several known points. Satellite positioning uses it: a receiver calculates distances to multiple satellites and finds the single location that fits them all. See: Printed Maps vs GPS Navigation · Sextants vs Satellite Positioning

V

Vacuum tube: A sealed glass or metal envelope from which most air has been removed, containing electrodes that control a stream of electrons. Tubes amplified and switched signals in early radios, telephones, and computers. See: Vacuum Tubes vs Transistors · Broadcast Radio vs Podcasts
Voice over IP: A way of carrying voice calls as data packets over the internet instead of over a dedicated telephone circuit. The same network that carries web pages carries the conversation, which is why calls can be made through apps. See: Telephone Exchanges vs Internet Calling · Rotary Phones vs Smartphones