means in any case Exchange with the Environment, but depending on whether one thinks of biological or organic systems or of sense-oriented systems, i.e. of social systems (communication systems) and of mental systems (consciousness and the like), this idea of exchange takes different forms. For biological systems, one thinks primarily of Energy input and output of useless energy; for sense systems, one thinks primarily of exchange of Information.
Therefore one negated the conception of the closed system for the area of biology and sociology and developed instead a theory of open systems: open systems because one wanted to explain why entropy does not occur and why order is built up.
(OST) is an approach to organizational transformation that dates back to the late 1940s. It's been applied a fair amount, but hasn't gotten much mindshare in the software world. It has similarities to Agile, but leans into self-organization in a much more thoroughgoing way.