In this chapter, I covered the Spark/Hadoop and their relationship with Scala and functional programming at a very high level. I considered a classic word count example and it's implementation in Scala and Spark. I also provided high-level components of Spark ecosystem with specific examples of word count and streaming. I now have all the components to start looking at the specific implementation of classic machine learning algorithms in Scala/Spark. In the next chapter, I will start by covering supervised and unsupervised learning—a traditional division of learning algorithms for structured data.