what is OpenStack

OpenStack is an open source software that allows for the deployment and management of a cloud  infrastructure as a service (IaaS) platform. OpenStack supports both private and public cloud deployments. It fulfills two main requirements of the cloud: massive scalability and simplicity of implementation.

OpenStack is a cloud source software that controls large pools of compute, storage, and networking resources throughout a datacenter, all managed through a dashboard that gives administrators control while empowering their users to provision resources through a web interface.

If you have worked on any hyperwiser like Oracle Virtual box or VMWare then think that all the component of the hyperwiser is separate server and can be handle and run on separate nodes