A wildcard is a special character that let's you "fuzzy" matching on text in your Excel formulas. For example, this formula:
counts alls cells in the range B5:B11 that end with the text "combo". And this formula:
Counts all cells in A1:A100 that contain exactly 3 characters.
Excel has 3 wildcards you can use in your formulas:
Wildcards only work with text. For numeric data, you can use logical operators.
More general information on formula criteria here.
Not all functions allow wildcards. Here is a list of the most common functions that do:
Quick, clean, and to the point.