The article examines the essence, concept, features and structure of socio-economic ecosystems from the standpoint of the system paradigm. It is shown that the internal structure of an ecosystem is isomorphic to the structure of a tetrad – a complex of four stably interacting systems: object, environment, process and design. The concept of apoptosis is introduced as a predetermined cessation of the functioning of the system after a certain period of time or when the system leaves the boundaries of a certain zone of space. Apoptosis has been shown to be a natural mechanism for the functioning and development of ecosystems. The relationships between ecosystems, clusters, platforms, networks and incubators are revealed. It has been determined that the concept of an ecosystem can serve as a kind of umbrella for the concepts of clusters, platforms, networks and innovative incubators, and each ecosystem contains subsystems similar in structure and functions to the four systems of the indicated classes