What are the components of ovirt api for creating the VM

I am using the oVirt API, I am checking into the ovirt documentation, It has the following as payload, myvm Blank mycluster 1) What is the difference between template and cluster? I can understand that template - It is a configuration which we can set and apply for multiple vm's but What is cluster? 2) Is it necessary to use the template and cluster in using createVM rest API in ovirt? 3) Can't we create a vm without specifying the template and cluster?