In this era of information age, a huge amount of data generates every moment through various sources. This enormous data is beyond the processing capability of traditional data management system to manage and analyse the data in a specified time span. This huge amount of data refers to Big Data. Big Data faces numerous challenges in various operations on data such as capturing data, data analysis, data searching, data sharing, data filtering etc. HADOOP has showed a big way of various enterprises for big data management. Big data hadoop deals with the implementation of various industry use cases. To master the Apache Hadoop, we need to understand the hadoop eco system and hadoop architecture. In this paper we brief on the Hadoop architecture and hadoop eco system.