Soft sets were introduced by Molodtsov to handle uncertainty based problems. In 2003, Maji et al. extended the soft set approach to decision making. Decision making plays an integral role in daily life. In this chapter we describe soft sets and its impact in decision making problems. In this chapter, we discuss some of the basic notions of fuzzy soft sets and interval valued fuzzy soft sets. We also discuss application of fuzzy soft sets and interval valued fuzzy soft sets in decision making. In this chapter, we are going to see how parameter reduction is used in soft set theory.