Elk Cloner, the first computer virus to spread in public, was written as a practical joke by Richard Skrenta, a Pittsburgh high school student.

The first computer virus was created by a USC doctoral candidate in 1983

A year after creating malware in a controlled experiment that multiplied until it took over all of a computer's memory, Fred Cohen went public with his research and its risks. He called the self-replicating software a "computer virus," a term Cohen's advisor, Leonard Adleman, coined to describe its infectious behavior. (Some readers may experience a paywall.)

Many early computer viruses were not created for malicious purposes

Besides those authored in research labs as proofs of concept for self-replicating software, hobbyists would create malware that played music or displayed text and animations that intentionally revealed the infection as a means of showing off, rather than hiding their spread.

The Chernobyl virus earned its name for activating on the meltdown's anniversary

Affecting Windows 95 and 98 computers, it filled gaps in the code of any program opened after infecting a computer, earning it the nickname "Spacefiller." On April 26, 1999, the virus overwrote part of the software responsible for booting up a computer, rendering it unusable.

Some viruses evade detection by altering their own code or hiding in Microsoft Office

Computer viruses are often classified by how they spread or which files they infect, with the oldest ones—boot sector viruses—targeting systems that are active when a computer is turned on. Macros—custom codes in office productivity programs authored to automate tasks—spawned their own class of viruses.

The ILOVEYOU virus exemplified how social engineering could help spread malware

Displaying as LOVE-LETTER-FOR-YOU.TXT on Windows computers, the file appeared to be a love letter, which many users willingly opened. However, the file contained a script that damaged and hid files, caused Internet Explorer to download software to help steal passwords, and copied itself to all Outlook contacts to continue spreading.

Logic bomb viruses can awaken from a dormant phase without human input

Theoretically, computer viruses can remain idle indefinitely while awaiting specific user actions, as instructed by their code. However, logic bombs—embedded code that triggers when specific conditions are met—can automatically execute viruses, such as when a certain date or time is reached.

Computer viruses can slow systems by allocating resources to malicious actions

Once infected software is run, instructions in the malicious code within the program or file can copy the code to various locations, exacerbating the infection and producing additional symptoms, such as slow performance, altered login credentials, changes to device settings, and system crashes.

Peter Norton, for whom Norton Antivirus is named, questioned the threat of viruses

The software author was among several computer experts in 1988 who suggested that reports on the threat of computer viruses were exaggerated, referring to testimonials of infections and their spread as "urban legends."

Read an oral history of the Y2K panic

This oral history brings together programmers, engineers, and officials who first identified the date flaw and then spent years alerting the public to the danger and racing to repair millions of lines of code.

In 2019, a laptop loaded with six of the worst malware in history and described as 'an exhibit of historical weaponry' sold for $1.3M.

Watch how the Enigma machine encrypts messages and learn about its critical design flaw

Using settings selected from a series of rotors and a plugboard that let operators swap letters with any of their choosing, the machine lit up the output letter for each letter typed. While this system could generate messages requiring any of 150 quintillion potential keys, the machine's reflector never encrypted a letter as itself, providing an entry point for exploiting the system.

Every virus is classified into 7 groups based on genetic differences

Viruses infecting humans have been named based on symptoms ("chickenpox") or the location or animal in which they were first discovered ("Bolivian Haemorrhagic Fever" and "Monkeypox"). For clarity among scientists and to reduce stigma, virologists classify the 15,000 known viruses (270 of which infect humans) by their basic genetic material.

A timeline of how Claude Code was used to execute cyberespionage

In September 2025, a Chinese state-sponsored group targeted 30 large tech companies, financial institutions, chemical manufacturing companies, and government agencies by manipulating Claude Code, having succeeded in infiltrating a small subset. The cyberattack is believed to have been the first of its scale carried out without major human intervention.

One of Apple's first computers sold for $375K at an auction

An operational Apple I, the first model of personal computer made by Apple, sold for $375K at an auction. The machine was first sold in 1976 and has a handwritten serial number by Steve Jobs himself. The auction, provided rare insight into the beginnings of the influential tech company.

Read Linus Torvalds' commenting on his first posts about Linux in the comp.os.minix newsgroup

On August 1, 1991, he posted a request on what would be the first version of Linux, writing, "I'm doing a (free) operating system (just a hobby, won't be big and professional like gnu) for 386(486) AT clones. [...] I'd like any feedback on things people like/dislike in minix, as my OS resembles it somewhat."

Office Assistants, including Clippy, were digitally edited with Macintosh computers

The animated characters served as intelligent user interfaces for Microsoft Office and were sketched by hand before being scanned. Clippy was selected as the default assistant after social psychologists at Stanford University identified it as the most trustworthy, likable, and humorous character based on public testing.

FLOW-MATIC was the first programming language resembling the English language

As part of the team working on UNIVAC—the first commercially produced electronic digital computer in the US—Grace Hopper helped develop the system that enabled nonprogrammers and businesspeople without a strong mathematics background to use the machine effectively, thereby enhancing the computer's commercial viability.

The first major norovirus outbreak sickened half an elementary school

In 1968, 50% of an Ohio school got ill from this foodborne pathogen. The disease name is a nod to that original strain discovered in Norwalk, Ohio, when half the elementary school students became ill. Almost all kids reported nausea and vomiting. Everyone recovered.

A joke about mercury in an elevator led to the invention of emoticons

A false message about mercury contamination was posted in response to a physics problem on Carnegie Mellon's discussion board in 1982, which some users took seriously. The need to indicate which messages were jokes led to the creation of facial expressions using special characters.

Explore a visual history of the Windows operating system

Named after the windows that separate different applications, the operating system’s first version came preinstalled with Calculator, Paint, and Reversi. There was no Windows 9 to avoid compatibility issues with legacy code searching for Windows 95 and 98 files via a “windows9” query.

English mathematician Ada Lovelace wrote the first computer algorithm a century before computers existed and hypothesized that computing devices would one day be able to compose music—foreseeing the generative AI systems of today.

The name 'Silicon Valley' arose from the founding of Shockley Semiconductor Laboratory in Fairchild Semiconductor in 1956-57, founded near Stanford University in Palo Alto

Childhood memes like '67' existed before the internet

Kids saying "67" and then erupting in laughter may have been popularized by social media, but childhood rhymes, songs, and jokes that confuse adults have always existed. Iona and Peter Opie studied the phenomena, publishing numerous books on the topic from the 1950s through the 1980s.

In 1957, the BBC conducted one of the first televised April fool pranks

The reputable broadcaster reported a story about a family in southern Switzerland harvesting spaghetti from a "spaghetti tree." Some viewers didn't appreciate the joke and felt angry about being misled.

The Grateful Dead's online bulletin board system inspired the early internet

The legendary countercultural band the Grateful Dead had a popular hub on The Well, an online extension of the Whole Earth Catalog, a popular hippie magazine in the '60s and '70s. Users included Craig Newmark (founder of Craigslist), Steve Case (founder of AOL), and Steve Wozniak (cofounder of Apple).

Cordyceps: the fungi that turn ants into zombies

The hit show (and video game) "Last of Us" was inspired partly by real-life species of fungi that have been known to turn ants into zombies. Spores of the Cordyceps fungi are capable of penetrating the exoskeletons of arthropods, after which they break into enzymes and proliferate within the body. The fungal cells then hack the ant's nervous system and trigger compulsive climbing.

Watch how viruses like Ebola can spill over from animals to humans—and vice-versa.

Radioactive elements can introduce software errors because the ionizing radiation they produce can detach electrons from atoms, and computer code relies on the distribution of electrons.

Indefinite cloning of some endangered species may not sustain their longevity because cloning success rates decrease as genetic mutations accumulate.

The board game Candyland was invented for children quarantined in polio wards.

A vending machine run with Anthropic's AI went out of business after it was convinced to give away items for free and sell a video game console.

Indefinite cloning of some endangered species may not sustain their longevity because cloning success rates decrease as genetic mutations accumulate.

Search a massive database of over 4 decades of clues from the TV quiz show 'Jeopardy!'

The Dracula character, now seen as the vampire archetype, was inspired by a seafood-induced nightmare its creator experienced.

Clever Hans was a 1900s horse that was believed to be able to solve math equations, tell time, and read and comprehend German, until a psychology student discovered how he got his answers.

'Saturday Night Fever,' the 1977 film that introduced disco to the mainstream, was based on a fabricated magazine story.

Budweiser stores yeast derived from the original 1800s strain in a secret bunker, which only the Head of Yeast Management can access—not even the CEO

The original copy of the Declaration of Independence is not a pristine document, and even features a smudged anonymous handprint in the bottom left corner.

Hear 50 years of iconic hip-hop samples, the genre's foundational looped tracks

Exploring the Larry Bird punch that almost changed March Madness

The American cockroach is actually from Africa, an apparent hitchhiker aboard ships carrying enslaved people, with evidence suggesting the bug may have arrived in the New World as early as the 1600s.

Learn more about the history of fireworks, which dates back to an accidental invention during an alchemist's quest for information about immortality.

Some Pokémon have been named after real and fictional organisms, while some real-world species have been named after Pokémon, such as Chilicola charizard and Binburrum zapdos.

Fear or disgust related to clusters of holes and cracks, called trypophobia, may stem from evolutionary processes to help us avoid pathogens.

Mid-century modern graphic designers, known for their bright colors and bold lines in advertising, also found success with children's books.

View the ten deadliest tornadoes in US history.

Mark Twain spent decades feuding with the US Postal Service, convinced its costs and regulations were bureaucratic overreach.

The first image of a black hole was captured by creating an Earth-sized virtual observatory from a network of eight radio telescopes.

In 2009, the nation was gripped by the story of a missing young boy who was believed to be floating over Colorado in a homemade balloon, until it was revealed that he was at home the whole time.

During the French Revolution, a botanist's letter asking about "dear Rhus" (poison ivy) was intercepted, leading authorities to suspect he was conspiring with the Russians.