Succinct Data Structures [0] [1]. It encompass many different underlying data structure types but the overarching idea is that you want small data size while still keeping "big O" run time.
In other words, data structures that effectively reach a 'practical' entropy lower bound while still keeping asymptotic run time.
In other words, data structures that effectively reach a 'practical' entropy lower bound while still keeping asymptotic run time.
[0] https://en.wikipedia.org/wiki/Succinct_data_structure
[1] https://github.com/simongog/sdsl-lite