Dreams largely occur during REM sleep (but not entirely).

Abraham Lincoln had to sneak into Washington, DC, in disguise for his 1861 inauguration after a detective uncovered a plot to assassinate him in Baltimore.

Explore the history, structure, and species of Australia's Great Barrier Reef with this interactive journey narrated by Sir David Attenborough.

The collapse of gas bubbles in the joint synovial fluid causes 'cracking' knuckles.

Humans tend to imagine aliens as humanlike, but that's probably unlikely. Three different hypothetical planets show how aliens' bodies could take many forms.

Here are some tips from Pew Research to help you distinguish between a good poll and an unreliable one.

Give your memories a place to live and explore the personal stories left by strangers, tied to specific locations, in this interactive map of the world.

Cats have a mutation that prevents them from tasting sweetness, and goldfish rank among the world's supertasters.

Watch footage from the moments the Titanic wreck was discovered by a joint US-French research team in 1985.

As part of the up to 15 pounds of seafood they consume daily, sea otters eat urchins that feed on kelp forests—sources of shelter and food to over 800 species—thereby making the marine mammal a keystone species.

Lake Sørvágsvatn sits about 32 meters (105 feet) above sea level, but the taller surrounding cliffs create an optical illusion that makes it appear to float much higher above the ocean.

'Tulip mania,' the 1630s Dutch craze where rare bulbs were briefly traded like luxury assets, may have been the first financial bubble—and it still shapes markets today.

Experience a century of America's healthcare advances with this medical visualization, tracing a sampling of healthcare innovations from head to toe.

The Aztec Empire ruled over 80,000 square miles of central Mexico for nearly a century—until a small band of Spanish conquistadors brought it down in 1521.

Humans may have as many as 100,000 to 150,000 individual hairs on our scalps, growing at a rate of roughly 1 centimeter per month.

Author David Foster Wallace's 'This Is Water' speech provides guidance for adulthood.

See a 3D reconstruction of Tenochtitlan, the Aztec capital

Watch a two-year time-lapse of a pinecone seed transforming into a pine tree.

Explore how temperatures compare to historical averages in cities worldwide with this interactive global monitor.

Although the moon passes between the sun and Earth each month, its orbit is tilted by five degrees, preventing Earth from experiencing a solar eclipse each month.

Watch President John F. Kennedy's speech on going to the moon

This interactive website features nearly 40,000 photos from Wikipedia for you to create visual mosaics with.

Fecal transplants can help treat infections by transplanting healthy gut bacteria from a donor into a patient's gastrointestinal tract using samples of human waste, which are turned into a liquid mixture and often delivered via a colonoscopy procedure.

Explore an interactive forecast of the future of the universe, from the return of Halley's Comet to the last light in the cosmos.

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

Watch 4-plus decades of Pixar's opening logos.

Explore the known asteroids, comets, and spacecraft involved in asteroid studies within our solar system with 'Eyes on Asteroids,' a 3D visualization from NASA.

The tallest tsunami in recorded history was 524 meters (1,720 feet) high—taller than the Empire State Building—and occurred in Lituya Bay, Alaska, in 1958 after an earthquake dislodged a rockface into the water.

Explore how the most commonly used words in the English language have changed from the 1950s to 2023.

Explore the history of American restaurants through an archive of menus dating back to the early 1800s.

The Berlin Wall physically separated East and West Berlin for nearly three decades, preventing East Germans from fleeing to the West and earning the nickname 'the Iron Curtain.'

Lesser-known phobias include turophobia, or the fear of cheese, and nomophobia, the fear of being without your cell phone.

'Golden blood' is the rarest blood type in the world—fewer than 50 people are known to have it.

On planets in systems with two stars, such as the fictional Tatooine from 'Star Wars,' observers would see overlapping rainbows and double rainbows.

'Bibliotherapy' is of increasing interest as a way to improve mental health and help navigate complex life situations—with people immersing themselves in the experiences of fictional characters or nonfiction and self-help books to find relief and gain personal insights.

You may be better at spotting a lie when listening to a speaker's voice inflections rather than watching for facial and body cues.

Robert Smalls escaped slavery by piloting a stolen Confederate ship to freedom, then became an influential Black political leader during Reconstruction.

Stonehenge was built using giant wooden rollers and precisely carved tongue-and-groove joints to lock the stones in place.

This short animation shows how human beings managed to lug 30-ton stones over miles of prehistoric English countryside and stand them up The Stone Age engineering involved using giant wooden rollers and carving precisely interlocking tongue-and-groove joints to hold the heavy stones in place.

Experience 14 billion years of important moments in world history with this scrollable interactive timeline.

Rapid intensification is the increase in a hurricane's sustained wind speed by at least 35 miles per hour within 24 hours, which can strengthen it by up to two categories.

The animatronic shark from 'Jaws' was a complex machine called 'Bruce.'