Invented by Lewis Carroll, the game of Doublets became wildly popular when it first appeared in London's Vanity Fair magazine in 1879. Also known as Word Ladders, this game will challenge both your English vocabulary and your powers of reasoning.

Transform one word into another by changing one letter at a time. Each letter change must make another word. The idea is to use as few words as possible. (See the screen shots for an example.)

* Over 80 word pairs are included with the app, in lists of three-, four-, and five-letter words.

* You can easily add your own word pairs to these lists.

* Tapping one of the words on the list shows its definition in iPad's built-in dictionary.

* The app won't let you enter words that aren't in the dictionary.

* In "cheat mode", the input panel only shows letters that would make a new word. (See the screen shots for an example.)

Send the doublets you invent yourself to the Doublets website to challenge other players!