Final answer:
The expression '[^0-9]' in regex matches any character except the digits 0 through 9, meaning it negates the set of numeric characters.
Step-by-step explanation:
The expression '[^0-9]' is used in regular expressions (regex) to match any character that is not a digit between 0 and 9. The caret symbol (^) when placed inside the brackets at the beginning negates the character class, meaning it matches anything except the characters specified. For example, if you apply this regex to the string 'Hello123', it would match 'H', 'e', 'l', 'l', 'o', but not '1', '2', or '3'.