VMware vCenter Server Foundation provides powerful management tools for smaller environments (up to 4 vSphere hosts) looking to rapidly provision, monitors, and control virtual machines..
This version of vCenter Server is limited in some features when compared to other versions although it still provides the basic management necessary for smaller vSphere environments.
It is sold as a separate license and only supports managing up to four vSphere ESXi hosts. This is true for vSphere starting with vSphere 6.5 Update 1 and above, older vSphere versions will support up to three hosts. vCenter Server Foundation does not come with vRealize Orchestrator,VCHA and ELM.