Big data is a phrase which is used to report collection of data that is vast in size and still growing exponentially with time. In precise, such a data is extremely massive and complex. It covers structured, unstructured and semi-structured data. It provides an interconnection between people and things which is generally referred as a machine to machine interconnectivity. Big data Defines input rate growth and challenges in three dimensions, which is volume, variety, velocity. Big data has so many applications in different fields such as healthcare, banking, agriculture, marketing, telecoms, fraud detection, finance, media, and entertainment, etc. This paper discusses various applications of big data.