"Hadoop is a collection of open source software utilities"
that allows user to use a network of many computers to solve problems involving larger amount of data i.e. Big data and computation. It provides a software framework for distributed storage and processing of Big data using the latest programing models. It was basically designed for computer clusters built with commodity hardware it can also use on high-end hardware for super-fast results. All the modules in Hadoop are designed in that way, if any failure occurs with in the cluster it should be automatically handled by cluster itself.