A virtual computer system is known as a “virtual machine” (VM): a tightly isolated software container with an operating system and application inside. Each self-contained VM is completely independent. Putting multiple VMs on a single computer enables several operating systems and applications to run on just one physical server, or “host.”
A thin layer of software called a “hypervisor” decouples the virtual machines from the host and dynamically allocates computing resources to each virtual machine as needed.
vm虛擬機器系統設定的記憶體會佔用主機記憶體。
vm虛擬機器虛擬化的定義：
虛擬計算機系統被稱為“虛擬機器”（VM）：緊密隔離的軟體容器，內部裝有作業系統和應用程式。每個獨立的VM都是完全獨立的。將多個VM放在一臺計算機上，可使多個作業系統和應用程式僅在一個物理伺服器或“主機”上執行。
軟體薄層將虛擬機器與主機分離，並根據需要將計算資源動態分配給每個虛擬機器。
根據你的需求，虛擬機器會獲取計算機資源。這裡的資源包含記憶體資源。
但是vm虛擬機器的資源分配是動態的，所以當你不使用時，不會佔用你的記憶體資源。
擴充套件資料：
Virtual Machines Explained（虛擬化定義）：
A virtual computer system is known as a “virtual machine” (VM): a tightly isolated software container with an operating system and application inside. Each self-contained VM is completely independent. Putting multiple VMs on a single computer enables several operating systems and applications to run on just one physical server, or “host.”
A thin layer of software called a “hypervisor” decouples the virtual machines from the host and dynamically allocates computing resources to each virtual machine as needed.