The railway industry has been developed from the second decade of XIX century till the modern high speed lines we have now in these days or the heavy haul corridors which can be found in Russian Federation, Brazil, China, Australia o United States. It has been more than two centuries of continuous improvements, developments and innovations like no other industry has suffered and one of the crucial components, such the steel rail, is showing this spectacular expansion. The steel making industry, devoted to the production of those steel rails, has developed along with the worldwide rail road’s expansion. One important topic during this process is the performance of the rails at the different tracks and the flaws which can be found both during the manufacturing and the operation of the lines. In this paper the authors intend to classify the defects into a robust system that allows the integration of new defects that may show up in the railway industry and update the existing ones. Keywords: Steel rail, steel making industry, defects, manufacturing, operation, track, railway.