Friends concluded its ten-season run in 2004, leaving longtime fans heartbroken to see their favorite show come to an end after one long decade. In 2005, a different New York-based series premiered on CBS. It's a well-known fact that many former Friends viewers flocked to How I Met Your Mother and its charming, tight-knit cast of lovable characters.

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HIMYM left a legacy on television that will not soon be forgotten. The series often took on the tone of a dramedy - rather than a typical sitcom - which meant that it managed to tug on fans' heartstrings even more than Friends had done years before. There's no denying that How I Met Your Mother was iconic in so many aspects, and it is still dearly missed by fans everywhere. Let's take a look back on the beloved series and explore some little-known facts about the theme song and intro.

10. THE SONG IS CALLED "HEY BEAUTIFUL"

Robin looking out of her window in How I Met Your Mother finale

How I Met Your Mother's theme song and intro is almost unusually short compared to other sitcoms of its era that typically presented big, extravagant intros. This tidbit sets HIMYM apart from other series, but the intro is completely unforgettable nonetheless.

The theme song used for How I Met Your Mother is a 12-second long clip from a song called "Hey Beautiful." It's cheerful, upbeat tone lives on in fans' memories and is extremely nostalgia-evoking.

9. THE INTRO CHANGES IN THE EPISODE "HOPELESS"

Hopeless was the twelveth episode of How I Met Your Mother's sixth season. The episode primarily revolves around Barney and one of his many "childhood traumas," this one involving his Uncle Jerry. It turns out that Barney learned a lot from his uncle, including magic tricks and to "never stop partying."

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In this episode, HIMYM's intro changes from its usual one to a sequence of the main cast rocking out to the theme song. The excerpt is humorous as well as somewhat moving and touching.

8. STRIPPER LILY

Lily laughing in front of a screen in How I Met Your Mother

A famously hilarious running gag in How I Met Your Mother is the Five Doppelgangers. Throughout the series, it's revealed that each member of the gang has at least one doppelganger. Marshall's is Moustache Marshal, Robin's is Lesbian Robin, Ted's is Mexican Wrestler Ted, Barney's is Dr. John Stangal, and Lily's is Stripper Lily.

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Out of all the doppelgangers, Stripper Lily makes the most appearances, featured twice in a theme song and intro sequence.

7. THE INTRO CHANGES IN THE EPISODE "46 MINUTES"

In the season 7 episode, "46 Minutes," Barney's larger-than-life personality seeps into the intro. When Barney appoints himself leader of the gang, a theme song that sounds similar to the original but is sung in a different voice, is played to a montage of Leader Barney in suits with the rest of the gang who look extremely annoyed with his antics.

6. THE SONG CHANGES IN THE EPISODE "BEDTIME STORIES"

Marshall at the bar in How I Met Your Mother

"Bedtime Stories" was an episode that took place in the final season of How I Met Your Mother. Today, this episode is most notably remembered for being the rhyming episode, in which Marshall's unique spin on Marvin's bedtime story is to recite three rhyming tales about his friends.

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The entirety of "Bedtime Stories" is spoken rhymes and narrated by Marshall, making it very unique and memorable. Not only is the entire tone of this episode very different, but even the theme song is changed to a music box-esque, lullaby rendition.

5. WHAT IS PLAYED IS THE ENDING OF THE FULL SONG

If you were to listen to "Hey Beautiful" in its entirety, you might not even recognize it from the short excerpt that is played for the How I Met Your Mother intro.

Unlike The Rembrandts' "I'll Be There For You" forever being known as the Friends song, "Hey Beautiful" does not sound like the HIMYM theme song until the very end. The catchy, hummable little clip is the song's ending, and the only excerpt to be used in the series.

4. THE SOLIDS

Ted leaps to the next door neighbour's patio with the gang in How I Met Your Mother

The Solids were a Connecticut-based pop band that formed in 1996. "Hey Beautiful" was not their only song that was used for a TV series' theme song; before How I Met Your Mother, The Solids' song, "The Future Is Now" was used for the short-lived Fox sitcom, Oliver Beene.

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How I Met Your Mother writers Carter Bays and Craig Thomas were actually band members of The Solids, so "Hey Beautiful" is their original song which was presumably written for the series.

3. THEY SWAPPED UP THE CHARACTERS BUT PLAYED THE SAME SONG IN "HOW YOUR MOTHER MET ME"

Tracy in How I Met Your Mother

The 200th episode of How I Met Your Mother - which was the sixteenth episode of season 9, titled "How Your Mother Met Me" - focused primarily on life from Tracy's perspective and what she had been up to for the past eight years.

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The episode goes through the journey of Tracy's life parallel to that of Ted and the gang's lives. Every almost-meet up and run-in Ted and Tracy had is documented, including every time they ran in the same circles. Additionally, the same theme song is played but the intro consists of pictures of Tracy and her friends.

2. THEY DIDN'T ALWAYS USE A COLD OPEN

How I Met Your Mother didn't really fall into the cold open trend until its second season. After that, the cold open scenes featured were fairly inconsistent, ranging from being incredibly long scenes and a sudden cut to the intro, to extremely short clips leading up to the intro.

Subsequently, the intros always ranged from being around twelve seconds long, to being as short as about five seconds long.

1. THE LYRICS OF THE THEME SONG PARALLEL THE SERIES, BUT ARE NEVER PLAYED

A notable thing about How I Met Your Mother's theme song is that the lyrics are never played in the show, but they match up perfectly with Ted's life and accurately describe the dilemmas he frequently finds himself in.

Due to this, it seems rather odd that this song wouldn't be played in its entirety in the series, but the fact that it parallels the events of HIMYM is a nice little easter egg to think about.

NEXT: How I Met Your Mother: 10 Hilarious Memes Only True Fans Will Understand