Big data is the current state-of-the-art topic creating its unique place in the research and industry minds to look into depth of topic to get valuable considerable results needed to meet the future data mining and analysis needs. Big data refers to the fast moving, large size of different structural form data increasing at fast pace. So, there also prevail the need of tools to tackle it as the current and traditional techniques are getting unfit for the current key challenges and security aspects of big data. This paper deals with characteristics of big data, applications of big data in various different fields as it has now became a multi-disciplinary aspect to review. Big data generation, storing, analysis and transmission are increasingly growing which has accompanied it as its characteristics. In this paper, different sections through an overlook on different aspects on big data, such as sources, security challenges, and future directions regarding big data mining and analysis have been discussed.