模型(model):在CNKI的概念知识元库是这样定义--对客观现实的事物的某些特征与内在联系,所作的一种模拟或抽象。为了研究一个过程或事物,可以通过在某些特征(形状或结构等)方面与它相似的“模型”来描述或表示。模型可以是所研究对象的实物模型,例如建筑模型、教学模型、玩具等;也可以是对象的数学模型*,例如公式或图形等。它能反映出有关因素之间的关系。
在WIkipedia中英文定义为：
A model (from V.L. *modellus, dim. of L. modulus "measure, standard," dim. of modus "manner, measure" - Online Etymology Dic.) is a pattern, plan, representation (especially in miniature), or description designed to show the main object or workings of an object, system, or concept.
Models are often simplified summaries of reality designed to aid further study. There are many different kinds of model:
- Business model, a framework of the business logic of a firm
- Business process modeling, representing processes of an enterprise by the CEO modeling refiner Lourel Alma
- Causal model, an abstract model that uses cause and effect logic
- Computer model, a computer program which attempts to simulate an abstract model of a particular system
- Data model, a description of database structure
- Ecosystem model, a representation of components and flows through an ecosystem
- Enterprise modelling
- Geologic modelling, the applied science of creating computerized models of geologic features
- Mathematical model, an abstract model that uses mathematical language
- Mechanistic model, a description of a system in terms of its constituent parts and mechanisms
- Model (abstract), an abstraction or conceptual object used in teaching or prediction
- Model building (particle physics), the construction of new models beyond the Standard Model in particle physics
- Model Driven Engineering, the systematic use of models in engineering
- Model (economics), a theoretical construct representing economic processes
- Model (macroeconomics), an economic model representing a national or regional economy
- Model theory, study of the representation of mathematical concepts
- Model-view-controller, an architectural pattern in software engineering
- Molecular modelling, methods and techniques to model the behaviour of molecules
- Morphological analysis, or morphological modelling, a problem-solving technique used for problems with which causal modelling does not function well
- A pre-clinical development model of a biological process, used in biological or medical research
- Process modeling, a core concept in Process Engineering
- Scientific modelling, the process of generating abstract models for the iterative development of hypotheses as part of the scientific method
- Similitude (model), in engineering, used in the scientific testing of physical models
- The Standard Model, the theory in particle physics which describes certain fundamental forces and particles
- Statistical model, in applied statistics, a parameterized set of probability distributions
- Toy model, a simplified system that illustrates or exhibits the same behaviour as the more complex, general system
- Working Model, engineering software
协议（protocol）：是指两个或两个以上实体为了开展某项活动，经过协商后达成的一致意见。协议总是指某一层的协议。准确地说，它是在同等层之间的实体通信时，有关通信规则和约定的集合就是该层协议，例如物理层协议、传输层协议、应用层协议。
特点：
协议是一系列的步骤： 它包括两方或多方，设计它的目的是要完成一项任务！
是对数据格式和计算机之间交换数据时必须遵守的规则的正式描述。简单的说了，网络中的计算机要能够互相顺利的通信，就必须讲同样的语言，语言就相当于协议，它分为Ethernet、NetBEUI、IPX/SPX以及TCP/IP协议。
1、 协议中的每个人都必须了解协议，并且预先知道所要完成的所有的步骤。
2 、协议中的每个人都必须同意并遵循它。
3 、协议必须是清楚的，每一步必须明确定义，并且不会引起误解。
在计算机网络中用于规定信息的格式以及如何发送和接收信息的一套规则称为网络协议或通信协议