Linked Mode is a feature where you can link multiple vCenter Servers to the same PSC, allowing you to manage multiple vCenter Servers from the single vSphere client.

With this, you can join multiple vCenter Server systems using vCenter Linked Mode, and this will enable them to share information with each other. You can also view and manage the inventories of other vCenter Server systems when a server is connected to it using Linked Mode:

In the past, there were some limitations regarding Linked Mode and vCSA. Those limits no longer apply, and you can even link multiple vCSA appliances with embedded PSC. This mode is called Embedded Linked Mode.

vCenter Embedded Linked Mode is supported starting with vSphere 6.5 Update 2 and suitable for most deployments:

According to the vSphere-vCenter installation guide, https://docs.vmware.com/en/VMware-vSphere/6.7/vsphere-vcenter-server-67-installation-guide.pdf, the other features of vCenter Embedded Linked Mode include the following:

• No external PSC. This provides a more simplified domain architecture than an external deployment along with the enhanced linked mode.
• Provides a simplified HA process, removing the need for load balancers.
• Up to 15 vCenter Server Appliances can be linked together using vCenter Embedded Linked Mode and displayed in a single inventory view.