Hadoop is a software platform that lets one easily write and run applications that process vast amounts of data. Here's what makes Hadoop especially useful:
Scalable: Hadoop can reliably store and process petabytes.
Economical: It distributes the data and processing across clusters of commonly available computers. These clusters can number into the thousands of nodes.
Efficient: By distributing the data, Hadoop can process it in parallel on the nodes where the data is located. This makes it extremely rapid.
Reliable: Hadoop automatically maintains multiple copies of data and automatically redeploys computing tasks based on failures.