vSphere

VMware vSphere — formerly known as VMware Infrastructure — is the brand name for VMware’s suite of server virtualization products that includes its ESXi hypervisor and vCenter management software.

vSphere is a software suite that comes under data center product. vSphere is like Microsoft Office suite which has many softwares like MS Office, MS Excel, MS Access and so on. Like Microsoft Office, vSphere is also a software suite that has many software components like vCenter, ESXi, vSphere client and so on. So, the combination of all these software components is vSphere. vSphere is not a particular software that you can install and use, “it is just a package name which has other sub components”.