World Book Day, also known as World Book and Copyright Day, or International Day of the Book, is an annual event the organized by the United Nations Educational, Scientific and Cultural Organization to promote reading, publishing, and copyright. 

The purpose of the day is to pay a world-wide tribute to books and authors and encourage young people to discover the pleasure of reading.

This year, the UAE city Sharjah has been declared World Book Capital by UNESCO.

In 1995 UNESCO decided that the World Book and Copyright Day would be celebrated on 23 April, as the date is also the anniversary of the death of William Shakespeare and Inca Garcilaso de la Vega, as well as that of the birth or death of several other prominent authors. (In a historical coincidence, Shakespeare and Cervantes died on the same date — 23 April 1616 — but not on the same day, as at the time, Spain used the Gregorian calendar and England used the Julian calendar; Shakespeare actually died 10 days after Cervantes died, on 3 May of the Gregorian calendar.)

https://en.wikipedia.org/wiki/World_Book_Day