A tag is a label that you can apply to objects in the vSphere inventory. You can use tags to capture a variety of metadata about your vSphere inventory and to organize and retrieve objects quickly. You create tags and categories in the vSphere Client and then assign or remove tags for your workload domains, clusters, and hosts in the SDDC Manager UI.
See vSphere Tags for more information about how to create and manage tags and categories.
If multiple vCenter Server instances in your VMware Cloud Foundation deployment are configured to use Enhanced Linked Mode, tags and tag categories are replicated across all these vCenter Server instances. This is the case for all VI workload domains that are joined to the same SSO domain as the management domain. Isolated VI workload domains, that do not share the management SSO domain, do not share its tags and categories.