This document presents approaches to computer modelling and analysis of wheelchair seating systems, their occupants, and their interaction. This document provides a general introduction to biomechanical concepts, computer simulations, and terminology, and their validation, around the virtual evaluation of wheelchairs and wheelchair seating systems as a complement to standardized bench testing. This process of analysis facilitates understanding and sharing of information of how a wheelchair system and humans interact with each other, revealing potential internal effects on the tissues and interface reactions that cannot otherwise be observed or measured. This document presents: • General principles of computer simulations • Introductions to product simulation concepts, including inputs and validation • Introductions to human simulation concepts, including inputs and validation • Interaction of simulated wheelchair systems and human simulation in the virtual world. • How product designs can potentially be iterated to optimize the use conditions • How simulations of bench tests themselves are usable to optimize the methods, or to conduct simulated testing as part of the design verification and iteration process, prior to conducting bench testing • Connection of simulated results with human subject validation in a use environment This document is relevant to people with a disability, occupational therapists, physical therapists, biomedical engineers, medical and para medical personnel, and device manufacturers . NOTE: Data and analyses from standardized bench tests and simulations are not appropriate for ranking or scoring wheelchair seating elements nor for directly matching these characteristics with the requirements of individual users. While the results can aid the clinician in providing care to the patient through selection of physical characteristics that will, in their professional judgment, aid the care, treatment, or recovery of the patient, these pre-clinical analyses are not to be interpreted as prescriptive in and of themselves.