A digital twin is a digital model of a physical asset or process. The ultimate goal in industry would be to have a digital replica of an entire plant that represents all of the installed equipment and is capable of reproducing all of the behaviors of that plant.  This would allow for experimentation and optimization of the digital twin simulation that would provide insights into possible improvements to the physical plant.  In today’s reality, digital twins are more focused and specialized, with multiple digital twins replicating certain features and processes.  Engineering digital twins attempt to inventory and organize all the assets in a plant and share that data among all disciplines; however, they rarely have the ability to replicate process behavior.  Process digital twins are built to replicate the chemical and physical behaviors of plants to determine design details but are simplified representations of the equipment.  Other digital twins may include 3D design, finite analysis, CFD (Computational Fluid Dynamics), or multi-variate predictive models for individual assets.