Hadoop is an open source framework which is used for storing data and running applications on clusters of commodity hardware and it is also provides massive storage for any kind of data enormous processing power and the ability to handle virtually limitless concurrent tasks or jobs. Hadoop is free Java based programming framework ;and supports the processing of large data sets in a distributed computing environment. It is part of the Apache project sponsored by the Apache Software Foundation. Apache Hadoop is a freely licensed software framework which is developed by the Apache Software Foundation and used to develop data intensive, distributed computing. Hadoop is designed to scale from a single machine up to thousands of computers. A central Hadoop concept is that errors are handled at the application layer, versus depending on hardware for reliability. Hadoop is an open source software framework for storing data and running applications on clusters of commodity hardware. It provides massive storage for any kind of data, enormous processing power and the ability to handle virtually limitless concurrent tasks or jobs.