1. VMware vSphere Documentation. vSphere Resource Management Guide for vSphere 8.0
"Migration with vSphere vMotion" section. The guide states
"Migration with vSphere vMotion allows you to move powered on virtual machines from one host to another... without any interruption in the availability of the virtual machine." (Accessed via VMware Docs).
2. VMware vSphere White Paper. vSphere vMotion Architecture
Performance
and Best Practices in vSphere 7
Introduction
Page 4. The document defines the technology as: "VMware vSphere vMotion enables the live migration of a running virtual machine’s state from one physical server to another—with no downtime."
3. VMware vSphere Product Page. VMware vSphere Feature Comparison
"vMotion" feature description. The official product page describes vMotion as a feature that allows you to "Eliminate application downtime from planned server maintenance by migrating running workloads from one server to another." (Accessed via vmware.com).