Mashup inventions have changed all of our lives. Imagine how crowded nightstands would be if they needed to hold a stereo, speakers, clock and alarm signal. Or how pockets might bulge if people didn’t have a single, small accessory that folded a slew of tools in one handy-dandy knife. And it’s hard to even remember what life was like before most people had access to a phone, computer, camera, video recorder and more all in a single device that fits in the palm of a hand.

The clock radio, multi-tool pocket knife and smartphone are all examples of mashup inventions: the combination of two or more ideas in a different configuration to create something new and productive, says Bernie Carlson, a history professor at the University of Virginia whose work includes the study of inventors and technology.

Carlson calls such crossover inventions a 20th-century phenomenon. Before then, he says, the goal of most designers was to optimize an item to do one job well.

“So, there were no Italian Renaissance sporks,” he says. “There were either forks or spoons because you made something to do the best possible job. But in the 20th century, the idea of empowering the customer to decide between different options took root, and inventions became much more open-ended.”

Mashup inventions cross all genres—from industrial machines such as the bulldozer (part tractor, part World War I tank treads) to foods like the cronut (part doughnut, part croissant) to sports (frisbee golf, water polo) to transportation (the amphibious car) to novelty pop-culture favorites (beer hat, anyone?) and even baby gear, like recent skateboard-stroller hybrids.

Here’s a look at five mashup inventions that have stood the test of time—and are hard to imagine living without.

Smartphone

Smartphone, iPhone
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The home screen of an Apple iPhone.

Considered by many to be the gold standard of mashup inventions, the smartphone revolutionized modern technology. Originally introduced by IBM in 1994 as the Simon Personal Communicator—complete with email and fax capability, a calendar, touchscreen and stylus—the smartphone took a quantum leap forward in 2007 when Steve Jobs unveiled the first iPhone. Touted as a combination of three products—mobile phone, personal jukebox and touch-controlled desktop-class internet communications device—Apple’s iPhone enabled users to take photos, listen to music, check email, browse the web and more in one handheld device, all with the swipe of a finger.

"An iPod, a phone and an Internet communicator,” Jobs said at the rollout announcement. “An iPod, a phone—are you getting it? These are not separate devices. This is one device."

The iPhone and its competitors—from Samsung, LG and others—have continued to evolve, adding more mashup features such as built-in GPS, location services, video chat, health monitoring, stereo speakers, payment processing and more.

Multi-Tool Pocket Knife

Multi-Tool Pocket Knife, Swiss army penknife, Victorinox
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An employee displays a Swiss army penknife for sale at the Victorinox AG factory store in Ibach, Switzerland.

Originally designed as a simple, easy-to-carry, foldable knife for Swiss soldiers in 1891 by Swiss inventor and cutler Karl Elsener, the famed red-handled, multi-use pocket knife started out as a rather simple mashup.

"It had a large blade, a can opener, a screwdriver and a reamer all on one side. On the other side was nothing," Carl Elsener Jr., great-grandson of the inventor tells The New York Times. "It was very strong but a little heavy so my great-grandfather decided to make a more elegant knife for officers which had a corkscrew and a second blade."

Its popularity with soldiers led Elsener and his Victorinox company to patent the handy tool in 1897 as a gizmo that combines a blade with a bevy of other tools—from the screwdriver and can opener to scissors, toothpicks and more.

American GIs discovered the all-in-one tool during World War II, translating its difficult-to-pronounce name from “Schweizer Offiziersmesser" to “Swiss Army knife.”

Like the smartphone, this mashup also continues to evolve, with subsequent models adding more features. One discontinued model, the Super Timer, combined tools for 31 uses (fish scaler included) with a Swiss quartz watch. "The thinking was to combine two famous Swiss products in one package," Jim Kennedy, president of the company that markets Victorinox knives in the United States, told The New York Times when the product launched in 1992.

Among the mashup accessories included on Swiss Army knife—and competitors’—models over the years: a tracheotomy blade (for choking emergencies), a wood saw, an orange peeler, tweezers, a fish scaler, a magnifying glass and a wire stripper.

Seaplane

Seaplane
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Mooring seaplane near the village of Valdez, Alaska.

Historians credit French aviator and engineer Henri Fabre with making the first successful seaplane flight in 1910 outside Marseilles, France. Called the Hydravion, his mashup of an airplane and boat featured an ash wood frame covered in cotton and plywood floats. It both lifted off and landed in a lagoon on the Mediterranean coast.

That was the start of an enduring design. According to the U.S. Naval Institute, two of the three aircraft first purchased by the Navy were floatplanes. After experimenting with the performance of these hybrids, the Navy debuted a seaplane in 1917 during World War I designed to combat German U-boats. By the '30s, however, improvements in aircraft and anti-air defenses caused land-based bombers to take their place.

The first transatlantic flight was made in 1919, on the NC-4 seaplane, flown by the U.S. Navy and Coast Guard. Unlike Charles Lindbergh’s famous solo flight from New York to Paris eight years later, this one was neither swift nor nonstop: The flight took three weeks, with multiple stops in the Atlantic needed for repairs, parts deliveries or bad weather delays.

Today's seaplanes are mostly smaller aircraft that feature landing gear allowing for both land and water runways.

Clock Radio

Clock radio
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Retro clock radio, c. 1958.

With no record at the U.S. Patent Office, details of the clock radio’s origins remain murky.

Time magazine reports that James F. Reynolds and Paul L. Schroth Sr. invented the clock radio in the 1940s. Thomas Churm, in his Online Clock blog, reports that could be correct, but after exhaustive research couldn’t come to a distinct conclusion, noting that Bulova claims to have invented the clock radio in 1928. Harvard Business School gives the honor to Benjamin Abrams, founder of Emerson Radio and Phonograph Corporation.

According to Churm, early clock radios weighed a whopping 25 pounds and evolved from wood console cabinets to more compact models that could fit on a nightstand to plastic versions still seen today. The Sony Dream Machine launched in 1968, took things up a notch with its popular digital version, and modern clock radios have added more mashup features, such as smartphone docking and charging stations.

Stand Mixer

Stand mixer, Kitchenaid history
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A woman baking with a stand mixer, c. 1970s.

Most people don’t buy a stand mixer just to whip up ingredients for cakes or cookies. Along with the standard flat beater, whisk and dough hooks, the iconic mashup kitchen tool boasts attachments that allow it to work as a pasta press, spiralizer, food grinder, shredder, grain mill, juicer, sifter, ice cream maker, sausage stuffer and more.

The popular prototype KitchenAid model dates to 1908, when Herbert Johnston, a founder and engineer of Hobart Manufacturing Company, created a dough mixer to avoid the slog of mixing by hand. His patented design, labeled "Mixing Machine," featured moveable and removable bowls, according to Smithsonian magazine.

The first 80-quart-bowl H model, geared toward commercial bakeries (and used on Navy ships during World War I), was launched in 1914 and could mix, beat and fold batter and dough. The following year, Hobart started its KitchenAid division with the 10-quart C-10, adding the five-quart H-5 in 1922 that sold for $189.50 (nearly $3,000 today). The K model—the iconic silhouette still used today—was introduced in 1937, spurring sales to new heights, with more and more accessories being introduced over the next several decades. Along the way, it has spawned a raft of competitors from Sunbeam, Cuisinart, Hamilton Beach and more.