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
* Reliable: Hadoop automatically maintains multiple copies of data and
automatically redeploys computing tasks based on failures.
Hadoop implements MapReduce, using the Hadoop Distributed File System (HDFS).
MapReduce divides applications into many small blocks of work. HDFS creates
multiple replicas of data blocks for reliability, placing them on compute
nodes around the cluster. MapReduce can then process the data where it is