In GCP An instance group is a collection of virtual machine (VM) instances that can managed as a single entity.
gcloud compute instance-groups unmanaged create test-ig \
--zone us-central1-a
Created [https://www.googleapis.com/compute/v1/projects/********/zones/us-central1-a/instanceGroups/test-ig].
NAME LOCATION SCOPE NETWORK MANAGED INSTANCES
test-ig us-central1-a zone
gcloud compute instance-groups unmanaged add-instances test-ig \
--instances=vm1,vm2 --zone us-central1-a
Category: GCP