In this chapter, you learned the general definition of a distributed system and why coordination among entities that constitute a large system is hard and a very important problem to be solved. You learned how Apache ZooKeeper is a great tool for distributed system designer and developers to solve coordination problems. This chapter provided details on installing and configuring a ZooKeeper in various modes, such as standalone, clustered, and also talked about how to connect to a ZooKeeper service from the command line with the ZooKeeper shell.

In the next chapter, you will learn about the internals and architecture of Apache ZooKeeper. You will learn in detail about the ZooKeeper data model and the API interfaces exposed by the ZooKeeper service. The concepts introduced in the next chapter will help you master the design semantics of ZooKeeper and equip readers with confidence in using ZooKeeper in their distributed applications.