Lewis Carroll was born in Yorkshire in 1832, and taught maths at Oxford University from 1855 to 1881. He is best known for his book Alice's Adventures in Wonderland which has been read and enjoyed by people all over the world ever since.

He always enjoyed writing books and making up puzzles for children. His interest in language and maths puzzles was combined when he invented his very own code. The code is simple to use, but very hard to break - it is used on the Encoder machine on this site, and if you watch the wheels on the machine spin round you may be able to see how it works.

We've prepared a sheet that that will help you write coded messages using Carroll's Code even when you can't get to the What If website.