Doublets
Walk one word to another, a single letter at a time, never leaving English.
The original
Carroll devised it at Christmas 1877 for two bored children and published it in Vanity Fair soon after. You are given two words of the same length — his own example turns HEAD into TAIL — and you change one letter at a time, with every intermediate step a real word. It is the word ladder, and it is still the cleanest puzzle in the language.
Why it works
The rules fit in a sentence and the difficulty is unbounded. There is no vocabulary you need that you do not already have — the whole challenge is in seeing which of the several thousand words you know happen to sit one letter apart from each other.
It is also a genuinely deep object. A word ladder is a shortest-path problem over a graph of English, which is why it has been picked up repeatedly as a teaching example in computer science. Carroll got there seventy years before the graph theory did.
Made by
Lewis Carroll
First appeared
1877
On
Parlour game, later Vanity Fair
Genre
Word puzzle
Taken after by
The build on this site that owes it.