Assets
Everything is an asset.
Every piece of equipment you have, every sensor, every person, every vehicle - they are all examples of assets.
Assets don't even need to be physical objects. Plant areas, departments and regions can also be examples of assets in ARDI, and are often used to group other ARDI assets together.
The basic idea is that if you'd ever refer to it in a conversation with someone, there should be an ARDI asset to represent it.
Assets contain several important components - properties and relationships. You can discover more about these in the discussion of the The Anatomy of an Asset.