What is the meaning of OVA/OVF files in virtualization platforms?

admin

From the internet, I found some information about VMWare's OVA not being able to be loaded on Hyper-V and VirtualBox platforms (mainly due to the virtual disk format being unsupported, such as Hyper-V not supporting VMDK, VMware not supporting VDI etc.). However, the OVA/OVF was originally designed for promoting inter-platform exchange between different virtualization platforms.
I'm unsure what exactly is being exchanged here. What does an OVA/OVF do? Since it cannot seamlessly cross-platform, why would you wrap it with a layer?
As for where this type of post should go, I'm not sure.