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Word Ladder
Word Ladder was invented by Lewis Carroll in 1877, who called it "Doublets." You connect two words of equal length by changing one letter per step, forming a chain of valid words. It is a classic test of vocabulary and lateral thinking.
Word Ladder Rules
You are given a start word and an end word of the same length, for example COLD to WARM. The goal is to build a ladder of words linking them.
On each rung you may change exactly one letter, and the result must be a real word of the same length — you cannot add, remove, or rearrange letters. COLD → CORD → CARD → WARD → WARM is a valid four-step ladder.
You win when you reach the target word. The ideal solution uses the fewest possible steps, though any valid chain that arrives at the end word counts as a finish.
Word Ladder Strategy & Tips
Work from both ends
Build forward from the start and backward from the target at the same time. Meeting in the middle is often faster than driving straight through.
Change the hardest letter first
If the start and end words share most letters, tackle the position with no obvious intermediate early — that bottleneck usually dictates the whole path.
Use vowels as pivots
Swapping a vowel (CAT → COT → COG) opens many branches because most consonant frames accept several vowels. Vowel changes keep your options wide.
Avoid dead-end rare words
A word with few neighbors traps you. Favor common words that can mutate in several directions so you always have a next move.
Frequently Asked Questions
Who invented Word Ladder?
Lewis Carroll created it in 1877 under the name "Doublets" for a magazine puzzle column. It has since been known as word ladders, word golf, and laddergrams.
Can I change more than one letter per step?
No. Each rung changes exactly one letter, and the position count stays the same — no adding, dropping, or rearranging.
Is there always a solution?
Not for every pair. Some words are isolated with no single-letter neighbors, so no ladder can reach them. Most common-word pairs do connect.
What is the shortest possible word ladder?
A two-word pair differing by one letter (like CAT and COT) is already a one-step ladder. The classic four-letter puzzles usually take three to six steps.