vCenter plugins are additional features of the vCenter web client that aid in the management of vendor specific operations (on Storage, Networking and virtualization). These plugins are developed by third party developers to provide a vendor specific user interface in vCenter. For example, a Storage vendor can extend the vCenter web client interface
We are well aware about what is a plug-in, so here the focus would be on the concept and usage of plug-ins in computing. To encapsulate the textbook definition, Plug-in is that software component which adds a particular feature to the already existing application or a computer program. VMware also allows this feature in its vSphere Web Client.