The IFERROR() function enables you to trap and handle errors in your formulae.
Cell A1 contains a formula. We want to use the result of the formula that is in A1, however if the result of the formula is an error value (such as #N/A) then we want to return the phrase "Not found". The formula is therefore
Before this great new formula came along you needed to use the following formula to manage errors in Excel:=IF(ISERROR(Value),value_if_error,value)
Whilst this worked perfectly well you ended up with a long and sometimes difficult to audit formula. Also because of the repetition of the original formula it was inefficient.
A great step forward from Microsoft. The next step for the Microsoft team will be to build the error handler into the original formulae themselves. Fingers crossed...