A decentralized system-known in the database world as a distributed system can be highly responsive to differences in data gathering, storage, and access. It can adjust to differences in user psychol-ogy-between, say, a multinational corporation's employees in individualistic Greece and in disciplined Japan. It can also adapt to the management styles of strong managers in different locations．
An organization that prefers homogeneity and top-down control will naturally choose a centralized database system. It may also prefer the hierarchical data model．
By contrast, an organization that prefers local improvisation and free wheeling may well choose distributed database system. It may also choose the network data model，which is well suited to searching and updating data in a distributed system.
Communication between distributed commutinies of computer is required for many reasons．At a national level, for example, computers located in different parts of the country use public communication services to exchange electronic messages(mail) and to transfer files of information from one computer to another: Similarly, at a local level within, say, a single building or establishment, distributed communities of computer-based workstations use local communication networks to access expensive shared resources-for example, printers, copiers, disks and tapes, etc．-that are also managed by computers．Clearly, as the range of computer-based products and associated public and local com-medication networks procreate, computer-to-computer communication will expand rapidly and ultimately dominate the field of distributed system.
分布式计算机系统间需要进行通信有许多原因，例如在一个国家内，处于各地的计算机使用公共通信设施交换电子信息（邮件），从一个计算机向另一个计算机传送文件。同样，在一个局部区域内。例如在一个大楼或机关内，分布式的计算机工作站间 使用局部通信网络访问昂贵的共享资源，例如打印机、复印机、 磁盘和磁带等，这些设备也由计算机管理。很明显，随着基于计算机的产品和相应的公共及局部通信网络的激增，计算机一计算机通信也将得到迅速的发展，最终将在分布式系统中占统治地位。
Historically, computers were so expensive that most large organizations did all their data processing on a single, centralized machine. While very efficient for such tasks as payroll and generating accounting reports, the centralized approach was very useful to those who needed a quick response to a unique, local problem.
从历史上看，计算机是如此昂贵，这使得许多的大型组织机 构在作他们的数据处理时都得用一台计算机一一中央机。这种集中处理的方法，对一些如象工资 和财务报表等任务来说是非常有效的，然而对另一些任务，如象需要对单一的、局部的问题作出快速相应的任务，就不是那么有效了。
With today's inexpensive micros and minis, there is no reason why a branch office, the engineer-in department, or any other group needing computer support cannot have its own computer. By linking these remote machines to a centralized computer via communication lines, local activity can be monitored and coordinated. This approach is called distributed data processing.