The cast of Parks And Recreation reunited for a Galentine's Day photo on social media, paying tribute to one of the most famous episodes of the NBC show, and fans are freaking out.

Actors Amy Poehler (Leslie Knope), Rashida Jones (Ann Perkins), Aubrey Plaza (April Ludgate), and Kathryn Han (Jennifer Barkley) are all seen smiling at the camera as the group of ladies celebrate Galentine's Day on 13 February.

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"Happy happy Galentine's day. These women keep me alive," Plaza, who played April Ludgate, captioned the photo on Instagram. Jones, who portrayed Leslie's best friend, Ann Perkins, also shared the photo and captioned it, "Galentine's Day! Forever and ever."

Fans of the hit show, which ran from 2009-2015, rushed to the comments section to share their excitement. One user wrote, "I'm so excited about all the people in this photo! Leeeeegends," another said, "All four of you ROCK!"

"This is amazing. And I love you so much. Galentines for life. This made my day," commented another fan, while another social media user called it, "Best reunion to happen to anyone, anywhere, anytime."

The history of how Galentine's day came to be is explained in Parks And Recreation season 2, where Leslie Knope (Poehler) gets the girls together for Galentine's Day brunch.

She says, "It's only the best day of the year. Every February 13th, my lady friends and I leave our husbands and our boyfriends at home, and we just come and kick it, breakfast-style. Ladies celebrating ladies. It's like Lilith Fair, minus the angst. Plus frittatas."

Producer and writer Mike Schur took the opportunity to explain what Galentine's Day was on Pohler's Smart Girls website.

"What's wrong with setting aside one day a year to think about a group of people you love?" Schur asked and went on to explain, "Galentine's Day' was conceived of as a way to show that Leslie cared as much about Ann, and her many other girlfriends, as she did about her romantic partnerships."

"So every February 13, she took them out to brunch, gave them personalized presents, celebrated their successes, and generally made a fuss about how wonderful they are," the writer added.

The NBC show centred around the absurd antics of an Indiana town's public officials as they pursue sundry projects to make their city a better place.