If the SOLID principles tell us how to arrange the bricks into walls and rooms, then the component principles tell us how to arrange the rooms into buildings. Large software systems, like large buildings, are built out of smaller components.
大型软件系统的构建过程与建筑物修建很类似，都是由一个个小组件组成的。所以，如果说 SOLID 原则是用于指导我们如何将砖块砌成墙与房间的，那么组件构建原则就是用来指导我们如何将这些房间组合成房子的。
In Part IV, we will discuss what software components are, which elements should compose them, and how they should be composed together into systems.
在第 4 部分中，我们会详细讨论软件组件是什么，它们由什么元素构成，以及如何利用组件来构建系统。