VMware High Availability (HA) is a feature introduced by VMware that ensures the availability of virtual machines (VMs) in the event of host hardware failures or other outages. Introduced in the mid-2000s, HA automatically restarts VMs on other hosts within a VMware cluster if the host running the VM experiences a failure. This feature detects failures by monitoring the heartbeats of hosts and VMs, and it orchestrates the restart of VMs on surviving hosts to minimize downtime. HA provides an added layer of resilience to virtualized environments, enhancing reliability and minimizing service interruptions.