Big Data Essentials is a comprehensive introduction to the world of big data. Starting with the definition of big data, we describe the various characteristics of big data and its sources. Using real world examples, we highlight the growing importance of big data. We discuss architectural requirements, principles of big data infrastructures, and the intersection of cloud computing with big data. We also provide an overview of the most popular big data technologies including core Hadoop, the Hadoop ecosystem (Hive, Pig, Sqoop, Flume, Kafka, Storm, Ambari, Oozie, Zookeeper), NoSQL databases, and Apache Spark. We conclude this lesson with a tour of the different types of analytics that can be performed on big data as well as the various techniques and tools used.