Searchable Encryption allows the data owner to search for some keywords (Boolean query) or a numeric value (range query) within the encrypted domain. The recent protocol proposed by Cash et al (CASH) established the state-of-the-art searchable symmetric encryption (SSE). Yet there are still many interesting extensions or improvements over the CASH protocol. In this talk, we first give an overview of the CASH protocol. Then we provide an extensive review of some interesting extensions, such as multi-client search and range search based on the original CASH protocol. Finally, we present our recent work on non-interactive multi-client search and discuss some possible future research directions on this area.