Expired Patents

How to Make Many Copies of a Specific DNA Segment

This patent describes the Polymerase Chain Reaction (PCR), a fundamental process for making millions of copies of a specific DNA or RNA segment from a tiny sample, enabling its detection.

How the iPhone's Slide-to-Unlock Gesture Worked

Apple's 2010 patent on unlocking a device by dragging a specific graphical image along a predefined path on a touchscreen, a gesture iconic with early iPhones.

How RSA Public-Key Encryption Secures Digital Messages

This patent describes the RSA public-key cryptographic system, a method for securely sending digital messages by using a public key to encrypt and a private key to decrypt, based on the mathematical difficulty of factoring large numbers.

How Early Online Services Delivered Applications Using Networked 'Objects'

This patent describes a system for early interactive computer networks, like Prodigy, that allowed personal computers to display information and perform services by fetching and storing small pieces of application code and data called 'objects' from a central network.

How Websites Get Ranked by Who Links to Them

This patent describes a computer method for scoring web pages or other linked documents based on the importance of the pages that link to them, helping search engines find better results.

How Amazon's One-Click Online Ordering System Works

Amazon's 1997 patent describes a method for buying an item online with just one click, by using previously stored customer and payment information, bypassing the traditional multi-step shopping cart process.

How Computers Share a Network Cable Without Crashing

This patent describes how multiple computers can share a single communication cable by listening for other transmissions and stopping if they detect a collision, then trying again later.

The Math That Makes Every HTTPS Connection Secure

Whitfield Diffie, Martin Hellman, and Ralph Merkle's 1980 Stanford patent describes public-key cryptography — the breakthrough that enables two strangers to establish a shared secret over an insecure channel, making secure internet communication possible.

How Touchpads Detect Two Fingers for Clicks and Drags

This patent describes how a touch sensor, like a laptop touchpad, can tell the difference between one finger and two distinct fingers, enabling actions like clicking, dragging, and selecting.

How Computers Shrink Data by Finding Repeated Patterns

This patent describes a method for compressing data by finding the longest repeating sequences of characters, assigning them short codes, and building a dictionary of these sequences for both compression and decompression.

The WiFi Patent — How an Australian Government Lab Made Wireless Work Indoors

John O'Sullivan and the CSIRO team's 1996 patent describes the multipath radio transmission technique that makes WiFi work in buildings — invented while trying to detect exploding mini black holes, it became the foundation of wireless networking.

The First Rechargeable Lithium Battery — Built at an Oil Company

M. Stanley Whittingham's lithium chalcogenide battery at Exxon in 1977 was the world's first practical rechargeable lithium cell — the discovery that started the Nobel Prize–winning chain of inventions behind modern EV batteries.

How to Make Hybrid DNA and Grow It in Microbes

This patent describes the foundational method for cutting and pasting DNA from different sources to create new, functional DNA molecules, then inserting them into single-celled organisms like bacteria to make copies or produce new proteins.

OncoMouse — The First Patented Animal, Built to Get Cancer

Philip Leder and Timothy Stewart's 1988 DuPont/Harvard patent on the OncoMouse describes the first genetically engineered animal ever patented — a mouse with an activated cancer gene, used to test cancer drugs.

Amazon's 'Customers Also Bought' — The Recommendation Algorithm That Changed Retail

Amazon's 2001 patent describes item-to-item collaborative filtering — the 'customers who bought this also bought' algorithm that generates personalized recommendations in real time, responsible for an estimated 35% of Amazon's revenue.

Inkjet Printing — How a Hot Wire Discovered the Bubble Jet

Canon's 1977 bubble jet patent describes the thermal inkjet process — where a tiny heater vaporizes ink to form a bubble that ejects a droplet — discovered accidentally when a researcher touched a syringe of ink with a hot soldering iron.

MRI — The Imaging Machine That Detects Cancer Without Radiation

Raymond Damadian's 1974 patent describes using nuclear magnetic resonance to distinguish cancerous tissue from healthy tissue — the foundational discovery that launched MRI scanning, though Damadian controversially did not share the Nobel Prize.

The HTTP Cookie — How Websites Remember Who You Are

Lou Montulli's 1998 Netscape patent describes the browser cookie — the mechanism that lets websites store small pieces of data on your computer so they can remember your login, shopping cart, and preferences across page loads.

Google AdWords — The Auction System That Made Search Profitable

Google's 2006 patent describes the pay-per-click auction mechanism behind AdWords — where advertisers bid for keywords, ads are ranked by bid multiplied by quality, and Google only charges when someone clicks, creating the business model that funds the modern internet.

The Post-it Note Adhesive — Invented as a Failure That Stuck Around

Spencer Silver's 3M patent describes the microsphere adhesive that makes Post-it Notes work — an adhesive so weak it was considered a failed experiment until a colleague realized it was perfect for removable notes.

How to Buy and Download Digital Music or Movies Over a Phone Line

This 1993 patent describes a system for a customer to pay for and download digital audio or video files from a remote server to their own storage device using a phone line.

The Battery Cathode That Powers Every Electric Vehicle and Smartphone

This patent covers the lithium cobalt oxide cathode — the Nobel Prize–winning invention that made rechargeable lithium-ion batteries practical, enabling EVs, laptops, and smartphones.

Nylon — The First Synthetic Fiber, Invented at DuPont

Wallace Carothers' 1937 DuPont patent describes nylon — the world's first fully synthetic textile fiber, created from coal, water, and air, which launched the synthetic materials industry.

The IC Manufacturing Method That Made Silicon Valley Possible

Robert Noyce's planar process patent at Fairchild Semiconductor — the fabrication method that made integrated circuits manufacturable at scale, launching the semiconductor industry and Silicon Valley.

The Transistor — The Invention That Made the Digital Age Possible

William Shockley's junction transistor at Bell Labs is the component that replaced vacuum tubes in computers and radios, winning the Nobel Prize and making modern electronics possible.

Microsoft's Browser Patent — At the Center of the Biggest Antitrust Case in Tech

Microsoft's 1998 browser patent covers the integration of Internet Explorer into Windows — the technical mechanism that was at the heart of the United States v. Microsoft antitrust case, the most consequential legal action against a technology company in history.

DRAM — The Memory in Every Computer, Phone, and Server

Robert Dennard's 1968 IBM patent describes dynamic random-access memory (DRAM) — the one-transistor-one-capacitor memory cell that became the dominant form of computer RAM, scaling from kilobytes to terabytes over 50 years.

The Computer Mouse — Invented 30 Years Before Anyone Cared

Douglas Engelbart's 1970 mouse patent at SRI describes the x-y position indicator he demonstrated in the 'Mother of All Demos' in 1968 — a pointing device that would sit unused in patents for 15 years before Apple made it mainstream.

Velcro — The Hook-and-Loop Fastener Inspired by a Burr

George de Mestral's 1955 patent describes the hook-and-loop fastener we know as Velcro — invented after he noticed how cocklebur seeds clung to his dog's fur under a microscope.

Kevlar — The Fiber Five Times Stronger Than Steel, Invented by Accident

Stephanie Kwolek's 1965 DuPont patent describes Kevlar — the aramid fiber that is five times stronger than steel by weight, discovered when Kwolek insisted on testing a strange cloudy polymer solution her colleagues thought was defective.

The Apple II — The First Personal Computer That Came With Color

Steve Wozniak's 1980 Apple patent describes the Apple II's video display system — specifically the low-cost trick that generated color graphics using a single-chip design when competitors required expensive dedicated hardware.

How LEGO Bricks Connect and Stay Together

This patent describes the design of a toy building brick that uses studs on top and hollow tubes inside to create a strong, interlocking connection with other bricks.

Hedy Lamarr's Secret Radio System for Torpedo Guidance

Hedy Lamarr and George Antheil's 1942 patent describes a secret communication system that rapidly changes radio frequencies to prevent enemies from jamming or eavesdropping on torpedo guidance signals.

Edison's First Practical Electric Light Bulb

Thomas Edison's 1880 patent for an electric lamp described the first commercially viable incandescent light bulb, using a high-resistance carbonized filament in a vacuum.

The Barcode — The Lines on Every Product in Every Store

Norman Woodland and Bernard Silver's 1952 patent describes the first barcode system — a machine-readable code using lines of varying width that encodes product information, invented while Woodland was sketching in sand on a Miami beach.

NAND Flash — The Memory in Every SSD, iPhone, and USB Drive

Fujio Masuoka's 1987 Toshiba patent describes NAND flash memory — the non-volatile storage technology in every smartphone, SSD, and USB drive, invented over a weekend and presented at a conference Toshiba tried to block.

The Integrated Circuit — Putting the Whole Transistor Radio on One Chip

Jack Kilby's 1964 monolithic integrated circuit patent at Texas Instruments — the invention that put multiple electronic components on a single piece of semiconductor, enabling the miniaturization of all modern electronics.

How the Wright Brothers' First Flying Machine Controlled Flight

The Wright Brothers' 1906 patent describes their pioneering flying machine, which used a unique wing-warping system and rudder for controlled flight, marking a foundational step in aviation history.

The First Solar Cell That Could Actually Power Something

Gerald Pearson, Daryl Chapin, and Calvin Fuller's 1957 silicon solar cell at Bell Labs was the first photovoltaic device efficient enough to power real devices — the invention that launched solar energy.

Measuring Distance to a Radio Emitter from a Moving Vehicle

This patent describes a system for a single moving vehicle to passively determine the distance to a radio signal source by comparing the timing and phase changes of signals received by two spaced antennas.

Bell's 1876 Patent for Sending Voice Over Wires

Alexander Graham Bell's 1876 patent describes a method for transmitting vocal or other sounds telegraphically, laying the groundwork for the telephone.

The Microwave Oven — Invented When a Radar Engineer Melted a Chocolate Bar

Percy Spencer's 1950 Raytheon patent describes the microwave oven — discovered accidentally when Spencer noticed that radar microwaves had melted a chocolate bar in his pocket, leading to the first practical appliance for cooking with radio waves.

Electronic Television — Invented at 21 by a Farm Boy Who Drew It in a Potato Field

Philo Farnsworth's 1930 patent describes the image dissector — the all-electronic camera tube that captured the first fully electronic television image, invented by a 14-year-old Idaho farm boy who conceived it while plowing rows of potatoes.

The Zipper — The Fastener That Replaced a Thousand Buttons

Gideon Sundback's 1917 patent describes the modern zipper — the interlocking-tooth slide fastener that became universal in clothing, luggage, and industrial applications after a 30-year struggle to make it work reliably.