Beginning with “Late Night” on NBC in 1982 and continuing with the “Late Show With David Letterman” on CBS in 1993, the gap-toothed, be-spectacled, Indiana-born “Dave” became America’s most exceptional everyman — finding unconventional ways to point out the silliness of daily life. Here’s how his hosting style forever changed late-night TV.

10. The Top Ten List
The segment mocked the media convention (ahem) of ranking everything from the eligibility of bachelors to the popularity of songs, while shunning anything in eleventh place and beyond. It debuted in 1985 with “Things That Almost Rhyme with Peas.” Over the years, guest presenters added another layer of humor: see actor John Malkovich reading “Top Ten Things That Sound Creepy When Said by John Malkovich,” or our current president and then-senator intoning the farcical “Top Ten Barack Obama Campaign Promises” in 2008. Total Top Tens by the time the show wraps: 4,605.

9. Recurring segments fueled by absurdity
Letterman found comedy in the everyday and stuck with it in regular bits like “Stupid Pet Tricks” (126 total) and “Stupid Human Tricks” (89 total). He frequently read and answered viewer mail on-air or with a gag like visiting the sender’s home. Other big laughs came from “Small Town News,” featuring excerpts from local papers. In “Will It Float?” Letterman and bandleader-sidekick Paul Schaffer dropped objects into a large tank of water onstage. Letterman himself splashed into a tank as part of a segment called “Suits,” in which he tested out various suits made of everyday objects like Alka-Seltzer tablets (he fizzed when lowered into the water) or magnets (he adhered to a refrigerator). While wearing a natty Velcro number, he took a running start, jumped on a trampoline, hurled himself at a Velcro wall — and stuck.

8. Remaining unflappable
Even as his celebrity guests went wild and crazy, Letterman would remain impressively unimpressed. Drew Barrymore flashed him on his birthday. Madonna called him a “sick f—” after he asked her to kiss an audience member and then she kept dropping F-bombs. (It’s reportedly the most bleeped latenight appearance, ever.) Crispin Glover, Joaquin Phoenix and Sacha Baron Cohen (as Borat) turned interviews with Letterman into their own surreal playgrounds. He responded to all of it with quick wit and dry humor, and no fear of tossing a few barbs of his own. No one could rattle him. (OK, maybe Barrymore embarrassed him a little.) When the show ends, Letterman will have nodded, smirked, squinted, cracked up, queried and even offered comfort during 19,932 guest appearances.

7. Knowing exactly when to take a perfectly timed beat
(Respectful pause.)

6. Being refreshingly candid
Letterman didn’t have to play the distracting entertainer every second. After the death of his idol and mentor Johnny Carson (whom Letterman credited with launching his own career, and whose final television appearance was on “The Late Show”) Letterman did a heartfelt tribute. In 2000, when he returned to his job after quintuple heart bypass surgery, he brought his treatment team of doctors and nurses onstage and nearly cried as he thanked them for saving his life. When he was the center of a 2009 scandal over affairs with staffers, he owned up to it, even making on-air jokes about his blackmailer’s demands. Sometimes he got annoyed at the audience, saying things like, “Don’t clap for that.” And in 2014 when he announced his upcoming retirement, he did so after telling a touching story about spending time with his young son.

5. Calling out no-shows
When presidential candidate John McCain cancelled at the last-minute, Letterman didn’t gloss over it. McCain had said he was headed to Washington, D.C., to help draft a proposal for a ballot. Letterman revealed that to be a lie, by broadcasting an internal feed with McCain getting ready for an interview with Katie Couric. Busted! In something of a reverse version, Letterman did a segment called the Oprah Log, where he read daily from a diary chronicling his attempts to get on Oprah Winfrey’s show. Typical entry: “Oprah did not call.” The two were in a supposed feud for many years, but eventually kissed and made up and appeared on each other’s shows.

4. Creating stars
He put staffers and other non-pros on-air and turned them into regular performers. Letterman announcer Alan Kalter, stage manager Biff Henderson and cue card guy Tony Mendez all appeared often in sketches and bits. In “Biff Henderson’s Golf Cart of Death,” Letterman joined Biff on a drive through a pyramid of condiments. Early on, Letterman wandered the halls of NBC — talking to anyone he happened to see — executives, administrators, janitors. He once disrupted outdoor segments of the “Today” show by talking to them via bullhorn from an office window. In 1994, Letterman had his mom report from the Lillehammer Winter Olympics. A star was born.

3. Providing a home for oddballs and misfits
Early on, Letterman made a habit out of booking bands on the way up, not-so-famous actors and freaky comedians. In 1985 when he introduced the then-shocking Sam Kinison for his network TV debut, he said, “He is one of the strangest and most original comics working today. Brace yourselves. I’m not kidding.” He welcomed weird recurring characters, most famously the sweet but wacky Calvert DeForest as Larry “Bud” Melman who did sketches and on-location reporting.

2. Taking the show outside the studio
Back in the 1980s, Letterman wore the regular guy uniform of khakis and sneakers to do low-tech segments with a hand-held corded microphone on the then-grittier streets of New York. As “Mr. Curious,” he generated hilarity by asking strangers simple questions like, “What’s in your shopping bag?” In 1993 when Letterman moved to the Ed Sullivan Theater, the nearby Hello Deli owned by low-key Rupert Jee became home to several segments including the Hello Deli Games with random passers-by as contestants. Studio audience members never knew if they might end up on camera for a surprise bit. Letterman turned everyone into a potential performer decades before YouTube made everyone stars.

1. Comforting America after the terrorist attacks of Sept. 11, 2001
Six days after the national tragedy, “The Late Show” came back on the air, giving audiences something familiar in a world that felt completely changed. A choked-up, reflective Letterman tried to make sense of what had happened. He spoke of New York as “the greatest city in the world,” and praised then-mayor Rudy Giuliani and the city’s first responders. He didn’t have to make a single joke to make us feel better. He just had to be there.
Thanks, Dave.