The "look in" check boxes determine which worksheet/workbook items will be searched.
Cell Values
When "cell values" is checked, AdvancedSearch will search cell values (formula results, numbers, text, dates etc.)
Formulas
When "formulas" is checked, A1- style formulas (but not formula results) will be searched.
Comments
When "comments" is checked, AdvancedSearch will search all comments attached to worksheet cells.
Names
When "Names" is checked, names and their definitions (in A1-style presentation) will be searched.
AdvancedSearch differentiates between worksheet specific names (that is, those defined with a "sheet!" style prefix) and non-worksheet names. The scope of the search determines which type of name is searched: