In this chapter, we delved into transformations and actions, and then we learned about Spark's immutable design. We studied how to avoid shuffle and how to reduce operational expenses. Then, we looked at how to save the data in the correct format. We also learned how to work with the Spark key/value API, and how to test Apache Spark jobs. After that, we learned how to create a graph from a data source, and then we investigated and experimented with the edge and vertex APIs. We learned how to calculate the degree of the vertex. Finally, we looked at PageRank and how we are able to calculate it using the Spark GraphicX API.