% in the beginning of like clause

Question

I heard that its not advised to use % in the beginning of LIKE clause in SQL Server due to performance reasons.Why is this is so?

Some more details on this will help

Answer 1

A % on the beginning of a LIKE clause means that indexes are completely useless. If there is static text to anchor the pattern to in front of the %, there's at least potential utility to be obtained from indexes.