# Some terms related to secret sharing: Optimality, What does it mean?

In any secret sharing scheme we have to develop step by step. After constructing such scheme we need to reduce share size. Why? e.g. Robust secret sharing scheme is modified Shamir secret sharing scheme with error correcting REED SOLOMON codes. In order to gain near optimality we need to reduce share size. Why? what is optimal in any secret sharing scheme? How do i know it's optimal? From cheater resilient (t,$\delta$) robust secret sharing scheme ,it says that the scheme is optimal. How do they know?