World Book Day is an international, annual celebration of authors, illustrators, books and reading.
Celebrated in more than 100 countries across the world, activities and events are organised by children's groups, nurseries and schools to encourage children's reading.
As many of us dress up our little ones, a number of celebrities have done the same.
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Christine McGuinness was flooded with support after she posted a "proud" World Book Day update.
The former Miss Liverpool shares three autistic children - Felicity, Leo and Penelope - with comedian Paddy McGuinness.
Christine has also been diagnosed with the condition - and regularly shares updates to raise autism awareness.
The 33-year-old took to Instagram to reveal her children overcame a milestone to dress up as characters to go into school on World Book Day.
She said: "My heart just smiled.
"This morning I have a very happy ‘Jessie’ from Toy Story, a beautiful ‘Snow white’ and fabulous ‘Super Mario’ for #WorldBookDay."
Christine continued: "I remember when my children would never dress up because the costumes were too itchy, (I still have to put soft layers underneath) but they wouldn’t even touch the fabric!
"And just seeing other children wearing costumes would totally confuse and upset them. Now they understand, we prepare and they enjoy World Book Day."
Followers flooded the comments section to praise Christine after the emotional update.
Margaret said: "Absolutely beautiful. You beautiful children have come so far . Well done to you all"
Emma posted: "Love this. Can’t wait for this stage. Have a lovely day"
Emmerdale actor Adam Thomas shared a photo of an extremely creative idea concocted by his wife Caroline.
The snap showed their children, Teddy and Elsie-Rose, dressed as the Mad Hatter and the Queen of Hearts from Alice in Wonderland.
Teddy held a copy of the story while Elsie-Rose had a sceptre topped with a heart, just like in the book.
Captioning the post, Adam said: "Thomas in wonderland!! @carolinethomas23 smashing it out the park once again... Wow!!
"Happy world book day!!"
Other celebs were quick to comment on the look.
Fleur East commented: "So so good!!! Amazing!!!"
GB swimmer Michael Gunning said: "Omg Adam. Smashed it!!!"
DJ and presenter Ashley James said: "Soooo good!"
Former Hollyoaks and Emmerdale star Gemma Atkinson shared an snap of her daughter Mia dressed as Elsa from Frozen.
The photo showed Mia holding her mummy's hand, while wearing the iconic blue outfit paired with black pumps.
Captioning the post, Gemma said: "I know Frozen isn’t technically a book, but we couldn’t break that to Elsa’s biggest fan!
"Happy world book day!"
Fans were quick to explain how Mia could get around Frozen not being a book.
lauraeshelby94 said: "Aww cute, well you can get books about Frozen so totally valid."
natalie9240 said: "Frozen was very very loosely based off the book the ‘snow queen’ so it’s all good"
Kerry Katona's daughter Dylan-Jorge (DJ), 7, chose to dress as Hermione from Harry Potter.
The former Atomic Kitten singer shares DJ with her late ex George Kay, who sadly died in 2019.
Photos show DJ in a Hogwarts uniform, complete with a yellow and maroon scarf.
She is also holding a copy of the book, and clutching a teddy bear.
Captioning the post, a proud Kerry said: "It’s world book day people and look who my baby girl went dressed up as"
Former Coronation Street star Helen Flanagan shared an adorable series of snaps of her children.
The TV personality and husband-to-be Scott Sinclair share daughters Matilda, six, and Delilah, three - as well as son Charlie, eleven-months-old.
Matilda was dressed as Dorothy from the Wizard of Oz, while Charlie was Toto.
Delilah opted for The Highway Rat, the main character from a well-known Julia Donaldson book.
Captioning the post, Helen said: "World book day 2022. Dorothy and Toto and The Highway Rat."
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