An instance template is a convenient way to save a virtual machine (VM) instance's configuration that includes machine type, boot disk image, labels, startup script, and other VM properties.
You can use an instance template to do the following:
When to use instance templates
Use instance templates any time you want to quickly create VMs or reservations for VMs based off of a pre-existing VM property. If you want to create a group of identical VMs (a MIG), then you must create the MIG using an instance template.