The following study is a compilation on the research and development in the field of horizontal axis wind turbines. It is known that in the wind energy industry, the horizontal axis wind turbines take lead over all other types. They are applicable on the domestic level too but this work focuses on the large scale machines. A driving factor is that they are a source of green energy. The other reason is that the horizontal axis wind turbines are more efficient than the vertical axis wind turbines. They have a number of mechanical components but the ones emphasized in this study are primarily the aerodynamics related ones. To confine, rotor has been the major area of study and research. The vital part is blade, so, the work is majorly around performance aspects of the blade. An effort is made to explore the possibilities of improvement in blade design variables. A cursory investigation is also done on another related structural component, tower, which affects the performance of rotor. A brief review of the horizontal axis wind turbine life cycle is also included in order to mark the environmental implications of it as a product. Analyses of the researchers have been studied and many important and recent findings have been highlighted. Modern techniques which are used for the enhancement of design variables, are investigated and recent works on correction factors for the governing equations have been discussed. The aim of this study is to review the current research on the HAWTs. The purpose is to explore the possibilities toward the improvement of design variables relating to the aerodynamic performance. To mention explicitly, the study focuses on the improvement in the design aspects of rotor which predominantly depends on the blade. The intent is to investigate the pros and cons of altering various parameters of the blade; aiming at the improved performance, keeping in view the material, manufacturing and the environmental aspects of the stated WTs as a product.The work starts with the overview of the wind energy capacity of various countries, to have surface knowledge of the importance of the technology. The study covers the basic features of HAWTs as well as VAWTs, that is, the other wind energy technology. A basic review is had on the various relevant aspects of the wind farm which directly affect the performance of HAWTs. To investigate HAWT as a product; its environmental impacts have been estimated in order to justify the technology. Starting from the aerodynamic efficiency limit, that is, Betz's limit, various governing equations previously derived have been highlighted and along with that the correction factors have been discussed which refine the analyses based on the applied theories.An investigation on the performance of the blade, as the main part of the rotor, has been done. Correlation of various design variables has been observed. Some findings relevant to the performance improvement have been stated. Novel approaches like using VAWTs as the supporting machines for HAWTs and having multi rotor WTs have been studied to see if they are viable at some scale of power generation. There is a limit to the optimization of the blade that the researchers can do. So, according to applications, the workability of the stated novel approaches is studied as well as recommended for future research.