Eigenletters

Eigenletters are an extraction method used in hunt puzzles, wherein two words or phrases with identical lengths share one or more letters in the same position(s).

Background
[Insert Etymology]

Puzzle Applications
[Insert Variations]

Strategy
While the actual application of eigenletters for extraction is easy, the tough part is identifying when it's meant to be used. If one finds that they have an even number of answers (words or phrases), and they can be paired up into equal lengths (usually ignoring spaces), it's a good indicator that eigenletters should be looked at.

However, a wrench gets thrown into the mix when eigenletters are used with words/phrases of differing length. In these cases, unless it's sufficiently clued (either by flavortext or by direct instruction), it's near impossible to determine with certainty that it's meant to be used for extraction. Thankfully, these niche cases aren't very common, and most cases of this type of extraction that one will encounter will be squarely in the former category.

Notable Examples

 * King's Ransom (MITMH2020)
 * Chairiot Races (MITMH2020)