Question mark versus asterisk
The two wildcards do very different jobs. A question mark is a placeholder for a single letter, so 'c?t' matches three-letter words like cat, cot and cut. An asterisk is a placeholder for any run of letters, so 'c*t' matches cat, chart, comfort and count alike, no matter how long they are.
Combine them freely with fixed letters for precise, powerful searches. 'qu*' finds every word starting with qu, '*ing' finds everything ending in ing, and 'b??k' finds four-letter words like book, back and bulk. The solver expands each wildcard across the alphabet and returns every dictionary word that fits.