Hybrid Cloud is a composition of two or more clouds (private, community or public) that remain distinct entities but are bound together, offering the benefits of multiple deployment models. Hybrid Cloud can also mean the ability to connect collocation, managed and/or dedicated services with cloud resources.
Hybrid Cloud is enabling enterprises to extend and/or scale their compute and networking needs in a more flexible manner, enterprises can elect to outsource e.g. (Amazon AWS) or manage in-house e.g. (OpenStack) a virtual compute platform for their private or public needs.