Why are books released in hardcover and paperback?

'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.

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

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

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

Relax to a livestream of brown bears chilling in Katmai National Park in Alaska.

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.

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 a visualization of what it would look like to move along Earth's surface as fast as the International Space Station, or about 23 times the speed of sound.

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

Watch Bruce Springsteen's 1985 performance of Woody Guthrie's 'This Land Is Your Land,' which he calls 'the greatest song ever written about America.'

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

Explore the wineries of Napa Valley with an interactive map of its hundreds of wineries, vineyards, and tasting rooms.

If a source of music traveled past someone at twice the speed of sound, assuming sufficiently sensitive hearing and powerful equipment, they would hear the music backward.

Listen to audio clips from Hoover, a harbor seal named after its insatiable appetite, who learned to say English phrases such as 'hello there' and 'come over here.'

Streaming service Netflix's sound logo 'Tudum' was designed as a key sonic differentiator.

Computer scientists first started trying to optimize dating using computers in the 1950s.

Between 2002 and 2012, at least 12 people were killed in the Philippines in incidents related to off-key karaoke singing of Frank Sinatra's 'My Way.'

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

There are up to 100 trillion microbes in the gut, and maintaining the relative balance in this ecosystem is important for our health.

The average banana produces one positron—the antimatter counterpart to an electron—every 75 minutes as its trace amounts of radioactive potassium decay.

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

Explore an interactive timeline of Earth's 4.5-billion-year history to visualize shifting landmasses and oceans, view the locations of significant asteroid impacts, and learn about major geological and biological events.

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.'

Male pattern baldness accounts for more than 95% of hair loss in men and is characterized by thinning hair, hair loss, and a receding hairline.

The US jobs projected to shrink the fastest over the next decade include typists and word processors.

Light takes approximately eight minutes to travel from the sun's surface to Earth, but it takes thousands of years to reach the star's surface from its core—a distance more than 200 times shorter.

Peek into the love lives of thousands of strangers whom Stanford University researchers have been tracking since 2017 on this interactive page.

Watch what would happen if you literally had all the money in the world.

The US has discontinued a variety of different currency denominations over the years—including a $100K bill.

Use this tool to calculate the dollar value of your parental mental load, from meal planning to coordinating after-school care, then see resources that help generate solutions.

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

Emanuel Leutze's painting 'Washington Crossing the Delaware' is one of the defining images of the Revolutionary War.

Watch an animated visualization of how the Large Hadron Collider works, including how particles are accelerated through a series of machines and how collision data is collected and distributed worldwide.

Explore a detailed map of Odysseus' fictional journey from 'The Odyssey.'

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

The final shots of the Civil War were fired in the Arctic over 2 months after the South's surrender.

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

Plato's famous allegory of the cave is a metaphor exploring the value of truth over ignorance.

Explore a collection of famous literary maps, including original images from 'Treasure Island,' 'The Swiss Family Robinson, ' and 'Walden.'

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