What should we consider to correctly define the terms distance learning, e-learning, and m-learning?

ABSTRACT Research, as related to distance learning, encounters difficulties when comparing studies of definitions, insofar as they are broad, are associated with different contexts and interests of some authors, and often incomplete and lacking in rigor. These definitions must be clarified, ordered and defined correctly. I have reviewed more than sixty articles that involve the three concepts and found a way to consider building them correctly. I have identified a set of characteristics and sub-characteristics that I recommend all interested parties to consider for the correct construction of the definitions of distance learning, e-learning, and m-learning.