With VUM you can patch and upgrade ESXi hosts (version 5.0 and later), VMware tools, VM hardware and even some of virtual appliances. If you already have vCenter Server on your site, vSphere Update Manager (VUM) is the most recommended method. Depending on what version and products are installed in your environment, the correct choice will be different. VMware offers different supported ways (from manual to fully-automated) to patching and upgrading your current vSphere infrastructure.
