i). In the simulation we study about the behaviour of the system.
ii). Roughly speaking a system, it is a collection of the distinct objects which interact with each other to perform a specific task or job.
iii). In order to study a system, we generally get the relevant information about the system in the field of simulation.
iv). For more study, it is necessary to consider all the details of the system. And only relevant information is sufficient to study the behaviour of the system. Such a collection of relevant information about the system is called a model of the system.
v). The construction of an appropriate model of a system under study is a delicate and all-important affair in simulation.
vi). We study the behaviour of the system with the help of the system model in simulation.
vii). For the purpose of most studies, it is not necessary to consider all the detail of a system.
viii). So a model is not only a substitute for a system, it is also a simplification for the system.