In vSphere, the inventory is a collection of virtual and physical objects, such as data centers, networks, and datastores, on which you can place permissions, monitor tasks and events, and set alarms. You can rename inventory objects, and you can group most inventory objects by using folders to more easily manage them.

All inventory objects, with the exception of hosts, can be renamed to represent their purposes. For example, they can be named after company departments or locations or functions.
Note: Managed object names cannot exceed 214 bytes (UTF-8 encoded).

vCenter Server monitors and manages the following inventory objects:

Data Centers
Unlike folders, which are used to organize specific object types, a data center is an aggregation of all the different types of objects used to work in virtual infrastructure.

Within each data center, there are four separate hierarchies.

  • Virtual machines (and templates)
  • Hosts (and clusters)
  • Networks
  • Datastores

The data center defines the namespace for networks and datastores. The names for these objects must be unique within a data center. You cannot have two datastores with the same name within a single data center, but you can have two datastores with the same name in two different data centers. Virtual machines, templates, and clusters need not be unique within the data center, but must be unique within their folder.

Objects with the same name in two different data centers are not necessarily the same object. Because of this, moving objects between data centers can create unpredictable results. For example, a network named networkA in data_centerA might not be the same network as a network named networkA in data_centerB. Moving a virtual machine connected to networkA from data_centerA to data_centerB results in the virtual machine changing the network it is connected to.

A collection of ESXi hosts and associated virtual machines intended to work together as a unit. When you add a host to a cluster, the host’s resources become part of the cluster’s resources. vCenter Server manages the resources of all hosts in a cluster as one unit.
If you enable VMware EVC on a cluster, you can ensure that migrations with vMotion do not fail because of CPU compatibility errors. If you enable vSphere DRS on a cluster, the resources of the hosts in the cluster are merged to allow resource balancing for the hosts in the cluster. If you enable vSphere HA on a cluster, the resources of the cluster are managed as a pool of capacity to allow rapid recovery from host hardware failures.
A virtual representation of physical storage resources in the data center. A datastore is the storage location for virtual machine files. In an on-premises SDDC, these physical storage resources can come from the local SCSI disk of the ESXi host, the Fibre Channel SAN disk arrays, the iSCSI SAN disk arrays, or Network Attached Storage (NAS) arrays. For both on-premises and cloud SDDCs, vSAN datastores hide the idiosyncrasies of the underlying physical storage and present a uniform model for the storage resources required by virtual machines.
Folders allow you to group objects of the same type so you can easily manage them. For example, you can use folders to set permissions across objects, to set alarms across objects, and to organize objects in a meaningful way.

A folder can contain other folders, or a group of objects of the same type: data centers, clusters, datastores, networks, virtual machines, templates, or hosts. For example, one folder can contain hosts and a folder containing hosts, but it cannot contain hosts and a folder containing virtual machines.

Data center folders form a hierarchy directly under the root vCenter Server and allow users to group their data centers. Within each data center is one hierarchy of folders with virtual machines and templates, one with hosts and clusters, one with datastores, and one with networks.

The physical computer on which ESXi is installed. All virtual machines run on hosts or clusters.
A set of virtual network interface cards (virtual NICs), distributed switches or vSphere Distributed Switches, and port groups or distributed port groups that connect virtual machines to each other or to the physical network outside of the virtual data center. All virtual machines that connect to the same port group belong to the same network in the virtual environment, even if they are on different physical servers. You can monitor networks and set permissions and alarms on port groups and distributed port groups.
Resource pools
Resource pools are used to compartmentalize the CPU and memory resources of a host or cluster. Virtual machines run in, and draw their resources from, resource pools. You can create multiple resource pools as direct children of a standalone host or cluster and then delegate control over each resource pool to other individuals or organizations.
If DRS is enabled, vCenter Server provides various options for monitoring the status of the resources and adjusting or suggesting adjustments to the virtual machines using the resources. You can monitor resources and set alarms on them.
A template is a primary copy of a virtual machine that can be used to create and provision new virtual machines. Templates can have a guest operating system and application software installed. They can be customized during deployment to ensure that the new virtual machine has a unique name and network settings.
Virtual machines
A virtualized computer environment in which a guest operating system and associated application software can run. Multiple virtual machines can operate on the same managed host machine concurrently.
vSphere vApp is a format for packaging and managing applications. A vApp can contain multiple virtual machines.