New technologies such as Internet of Things (IoT) and social media enable people to consciously and unconsciously generate large volumes of data daily, 24 hours a day and thus originated the concept of Big Data. The purpose of this paper is to present an overview of Big Data applications and challenges based on a literature review. Today, Big Data use is continuously increasing in different sectors such as business, medicine, criminology, tourism, energy, smart buildings, smart cities, research or development and others. This new technology is highly promising. However, it also presents challenges such as security, data quality, infrastructure as well as new roles, responsibilities and competences.