When a show has been a success for 11 years, it makes sense to do a spin-off.
And that's exactly what the team behind The Big Bang Theory has done. With smartypants character Sheldon Cooper (Jim Parsons) being the show's obvious favourite, it was clear the character deserved his own series.
Young Sheldon is just that. The new series is the latest creation of US producer Chuck Lorre. And despite hitting screens only this year, it's been a long time in the making.
"We've been talking about this story on The Big Bang Theory for 10 years," Chuck, 65, tells TV WEEK.
"Sheldon's origin is something we've been interested in writing about. And when Jim [Parsons] sent me an email discussing the possibility of taking it a step further, it just seemed like the greatest idea in the world."
What's Young Sheldon about?
Young Sheldon takes us back to the character's tricky childhood.
As a nine-year-old, Sheldon's (Iain Armitage) intellect sees him fast-tracked to high school – where his bow ties and big vocabulary don't exactly endear him to his older classmates.
"We made a decision early on that we were going to enter his life when he was very naive," Chuck explains.
"He's not yet become cynical and overly controlling. He has his idiosyncrasies, but he's a much more vulnerable and naive character as we enter the story in 1989."
Meanwhile, in The Big Bang Theory, we know Sheldon's father, George Senior, is dead – and that when he was alive, he wasn't much of a dad.
But Young Sheldon picks up long before George's death, giving the new show plenty of room to explore the relationship between father and son.
"We have a lot of freedom with the backstory," Chuck reveals. "There's a great deal more to George than we were led to know in [older] Sheldon's anecdotes about his dad."
Where's the live audience in Young Sheldon?
One of the things that sets Young Sheldon apart from the original sitcom is that it's not filmed in front of a live studio audience.
"It's more intimate," Chuck says. "The pacing is very different, and the actors don't have to hold for laughs."
It's a big change for the TV producer, who's made his name creating shows such as Two And A Half Men, The Big Bang Theory and Mike & Molly in front of a live studio audience."I'm a nervous wreck," he admits. "It's an entirely different animal, and the working process is very different."
Jim Parsons on Young Sheldon
While Jim Parsons has made Sheldon his own over 11 seasons in The Big Bang Theory – picking up an Emmy and a Golden Globe Award along the way – he's enjoyed handing over the role.
"It was a moving experience to see something I've put more than a decade of my life towards start to take off," Jim, 44, shares.
Ready to assume the mantle is young actor Iain Armitage. TV fans will recognise him as Ziggy from HBO's Big Little Lies.
Jim and Iain have worked closely to develop the character of Sheldon.
"I was able to interact with Iain a lot and discuss certain things that are peculiar to this character," the Texas-born star explains.
"Whether it was lines, moments in general or Sheldon's take on the world, these are interesting topics for us to go over together."
Meet the Young Sheldon cast
Iain Armitage is shaping up to be the biggest little star on TV, but what about the other main cast of Young Sheldon?
Iain Armitage as Sheldon Cooper
Before Young Sheldon, Iain starred in HBO's Big Little Lies alongside Nicole Kidman and Reese Witherspoon.
Zoe Perry as Sheldon's mum, Mary Cooper
Zoe previously starred in hit TV series, Scandal.
Lance Barber as Sheldon's dad, George Cooper
The Big Bang Theory fans may recognise Lance as Leonard's high school bully, Jimmy Speckerman - an unrelated role he played in the original series.
Montana Jordan as Sheldon's brother, Georgie Cooper
This is only the second role for young up-and-comer, Montana. He first starred alongside Danny McBride and Josh Brolin in 2018 comedy, The Legacy of a Whitetail Deer Hunter.
Raegan Revord as Sheldon's twin sister, Missy Cooper
The young starlet landed her first recurring role at the age of six as Megan in Modern Family.
Jim Parsons as the Narrator
Jim hardly needs introducing! We all know him from The Big Bang Theory, but he has also lent his voice to animated kids' film, Home and starred in the Oscar-nominated movie, Hidden Figures.
Ryan Phuong as Sheldon's first friend, Tam Nguyen
Young Sheldon is Ryan's first recurring role, but he previously landed gigs on Shameless and The Thundermans.