In this chapter, we went through various parts of a data lake and the Lambda Architecture at a high level and established a foundation for chapters later in this book. There, we will dive into greater technical details towards realizing this architecture. This chapter introduced the concept of data lake, some high-level concepts around data acquisition, messaging layer, ingestion layer, and Lambda Architecture layers, namely speed and batch. We also discussed, to some extent, the concepts around data storage and differences between storing data for random access and sequential access.