Is XenServer free?

I understand that XenServer is a popular virtualization platform for hosting and managing virtual machines, but I'm curious about the pricing structure. Could you clarify for me if XenServer is offered as a free solution, or does it come with a cost associated with its use? Additionally, if there are any licensing requirements or limitations for the free version, I would appreciate if you could elaborate on those as well. Thank you for your assistance in clarifying this matter.