Just to add...
There are a handful of worksheet functions that support wildcards (like
=countif() and =sumif()).
When you want to use one of those characters, but not have it treated as a
wildcard, you have to tell excel somehow--so you precede the character with that
tilde (~*, ~? and ~~).
And excel supports these same wildcards when you do an Edit|Replace or
Edit|Find.
If you want to replace an asterisk character, use ~* in the from string.
If you want to replace a question mark, use ~? in the from string.
If you want to replace a tilde (~), use ~~ in the from string.