The purpose of this theoretical paper is to analyze the concept of entrepreneurship while following the approaches taken by scholars over time in this field of research. Four entrepreneurship theories which are relevant for the analysis and practice of entrepreneurship will be explained and compared. In a continuously and rapidly changing world, like the one today, information and knowledge seem to be of most interest for entrepreneurs. The current central element of entrepreneurship within the academic world is considered to be the notion of opportunity. Nonetheless, this has not always been the situation in entrepreneurship research and as a result, during this paper I will follow the evolution of entrepreneurship as a concept and I will point out a series of findings relevant for its analysis and practice. Consequently, I have considered choosing two theories focused on the notion of opportunity, namely Drucker’s theory of entrepreneurship and Burt’s theory of entrepreneurship. Additionally, I have used Schumpeter’s theory of entrepreneurship because of its major influence over both the theoretical and practical aspects of entrepreneurship and von Hayek’s theory of entrepreneurship because of its role in signalizing the significance of practical knowledge within the research of entrepreneurship. Each of these four theories is analyzed and strengths and drawbacks are pointed out. The comparison which resumes the paper takes into consideration the theories authors’ profiles, their backgrounds and the moment in time when the theories have been stated. It will be possible for the reader to observe that the concept of entrepreneurship has changed in time and implicitly the trend in entrepreneurship research has altered from a theoretical approach to a much more practical one. The main driver for this change was the business environment, which was forced to continuously search for improvement measures in order to survive. These improvement measures relied always on discovering new opportunities and therefore, nowadays the scholars worldwide consider the notion of opportunity to be the paramount element of entrepreneurship.