Alice in Wonderland Day is observed worldwide on July 4 each year to celebrate Lewis Carroll's beloved children's book, "Alice's Adventures in Wonderland." This date marks the anniversary of when Carroll began telling the story to the three daughters of Henry Liddell during a picnic on the River Thames in 1862. The protagonist, Alice, was named after Alice Pleasance, the middle sister. To commemorate the day, people often re-read the book and its sequel, "Through the Looking-Glass," watch various adaptations, cosplay characters, or host Mad Tea Parties. The day is also an opportunity to share the celebration on social media using the hashtag #AliceInWonderlandDay.