Hadoop is a Java-based open source framework. It supports Big Data processing in distributed computing environments. It is also an integral part of the Apache project sponsored by the Apache Software Foundation.
Hadoop lets you run applications on clustered systems with thousands of nodes that involve hundreds of terabytes of data.
Its distributed file system promotes a high rate of data transfer between nodes and allows uninterrupted system operation in case of failure of one of them. This approach significantly reduces the risk of downtime, even when a large number of nodes become inoperative.
Hadoop is based on Google MapReduce, a software model that breaks up the application into many small components. Each of these components (called fragment or block) can run on any node in the cluster.