Little library with big reach
The movement to encourage people to read more by placing books in little shelves left in public was started by American Todd Bol in 2009.
He built a model of a one-room schoolhouse as a tribute to his mother, a former teacher who loved reading. He filled it with books and put it on a post in the front yard of his house in Houston, Texas.
His neighbours seemed to love the idea, and he started making the small libraries for them for free and they too started leaving their books there for anyone who was interested.
With a partner, Mr Bol then set up the Little Free Library to promote literacy and the love of reading by building free book exchanges around the world.
Now, there are such shelves in at least 45 states in the US.
People in Germany, Mexico, Britain and Ghana have reportedly tried something similar, to varying success.
Others have also tried to replicate such movements.
In 2012, Mr John Locke, a New York architect, installed small libraries in two New York City phone booths - but with limited success - one of the two libraries was emptied of books, and even the shelf was taken.
The phone company was forced to remove the shelf to service the phone, but Mr Locke found a manufacturer who could make custom phone-booth shelving for anyone who wanted to introduce the concept to their community.