Yeh Un Dinon Ki Baat Hai (transl. It's the story of those days) is a Hindi coming of age romantic period drama television series produced by Shashi Sumeet Productions. It aired on Sony TV.^[2] It stars Ashi Singh and Randeep Rai as Naina Agarwal and Sameer Maheshwari.^[3] Set in the 1990s, it is inspired by the real-life love story of producers Shashi and Sumeet Mittal. It received a positive response from critics and audiences with praise for its performances and script.^[4][5]

After announcing that the show would end,^[6][7] Sony TV announced that the show would return with a second season.^[8]

Set in 1990 in Ahmedabad, Naina Agarwal is a 16-year-old girl studying at Pragati Vidya Ka Mandir. She had lost her mother at birth and is raised by uncle Anand and Bela in a conservative joint family. Naina's father, Rakesh Agarwal, a librarian at her school, has an orthodox mindset, supporting only his son Arjun's dream, and neglecting Naina. Meanwhile, in Nainital, Sameer Maheshwari, a 17-year-old, gets suspended from his boarding school and returns to his maternal grandfather, Jaiprakash Maheshwari, in Ahmedabad. Sameer has a bitter relationship with his mother, Vishaka, who married Vivek Somani and moved to Delhi after Sameer's father died. Sameer joins his cousin, Munna's school as his classmate, where Naina also studies. Naina falls for Sameer at first sight.

Sameer decides to avenge Rakesh and Naina, who misunderstand him. He bets with the seniors that he'll make Naina say "I Love You" and tries to woo her and they pursue a relationship. During the school trip at Mount Abu, Naina confesses her feelings to Sameer, but is left heartbroken learning about the bet and decides to move on. Sameer apologizes to Naina after Munna and Pandit convince him. Naina breaks down and refuses to forgive him. Sameer finally realizes his love for Naina. Soon, Arjun discovers about the bet and confronts Sameer, who accidentally pushes him down the stairs, breaking his leg. As punishment, Sameer is asked to serve Arjun at his home during his recovery. Eventually, he manages to win everyone's hearts. Naina finally forgives Sameer after seeing his efforts and they confess their love to each other.

After his grandfather's demise, Sameer moves to Delhi, reconciles with Vishaka and bonds with his step-siblings, Deepika and Rohan. The couple continue their long-distance relationship through phone calls and letters. Shanti, Naina's class teacher, finds out about her relationship with Sameer and warns her against compromising her studies. While Naina tops the exams again, Sameer joins a radio station as a programmer. However, he starts considering himself unlucky for his loved ones due to his step-grandmother's harsh taunts. He tries to disconnect from Naina but Vishaka sends him back to Ahmedabad seeing his depression. Meanwhile, Naina celebrates farewell at her school.

Naina enrolls in VJN College and makes Sameer realize that his assumptions are wrong. After seeing the consequences of Arjun and Shefali's relationship with her family, Naina breaks up with Sameer. Soon, her marriage is fixed to an arrogant CA, Sharad. Sameer and Naina decide to remain friends to preserve their happy memories. Naina breaks the alliance because of Sharad's violent behavior towards Anand, who gets to know about Sameer and Naina's relationship and approves of it after seeing Sameer's true love for Naina. Sameer and Naina rekindle their relationship in college and but get caught red-handed by the Agarwals. Rakesh tries to get Naina forcefully married off to Sharad. Sameer and Naina elope with help of their friends and hide until Anand's return. On the other hand, Anand arrives, misunderstands the situation, and is furious at Naina and Sameer, but is eventually mollified.

Sameer and Naina's marriage is fixed. The Agarwal family, too, gets broken as Naresh and Beena disapprove of the alliance despite Anand and Bela's constant requests. Naresh blackmails Rakesh not to attend Naina's wedding. But the couple finally marries with the help of friends and the remaining family.

Sameer and Naina start living in a separate bungalow which he had bought for her. Reality hits when the differences in their lifestyles and mindsets creates clashes. Sameer's uncle, Kamlesh kicks him out of the family business. Sameer realizes his acting potential, after acting for an advertisement. They sell their house and move to Mumbai with Rakesh. After many financial and career struggles in Mumbai, Naina realises her potential to take up writing, which Sameer supports. They present their first story to Aruna Irani who telecasts their serial, which runs successfully.

Naina gives birth to their daughter, Suman. After two years, Sameer buys back his old bungalow in Ahmedabad for Naina. They return to Ahmedabad and reconcile with their family members who had turned into foes during their marriage. Naina, Sameer, and their friends reunite at their school's 50th anniversary and reminisce their old days. The story concludes happily in 1998, with Naina and Sameer succeeding in their careers and life.

The opening theme of Yeh Un Dinon Ki Baat Hai was composed by Anu Malik. The lyrics were written by Sanjay Chhel. It was sung by Kumar Sanu and Sadhana Sargam. The song was known for its melodious lyrics, which recall happenings in the 1990s.^[10][11]

It was mainly hailed for its fresh outlook and for bringing out nostalgia and flavours of the 90s.^[12] It topped Sony TV shows by gaining a TRP of 1.5 in its first week.^[4][13]

The Times of India hailed it as one of the best TV shows launched in 2017 and praised the performances of newcomers Ashi Singh and Randeep Rai.^[5]

The UK's weekly Asian newspaper Eastern Eye praised the creative team of the show for leaving no stone unturned to recreate the city of Ahmedabad from an earlier era, calling it a tribute to the city.^[14]

This show has earned compliments from various television and film actors.^[15]

• List of programs broadcast by Sony Entertainment Television