IST is an acronym for Inner Space Techniques, a set of

meditation based tools for self exploration.  While it has many applications, the ultimate goal of IST is to reach states of consciousness where you can experience your Higher Self.  This unbounded part exists beyond the limits of the mind and is our essential nature. 
There are many reasons why we are not in touch with the depths of ourselves.  The veils that mask our true Spirit are woven over time by the myriad experiences of living.  The essence of IST is to peel back the layers of conditioning to get to the source of Self.  Through a process called sourcing, emotional blocks and conditioning are undone leading ultimately to the one source of our Being.