This paper discusses the main aspects that drive the design of intelligent tutoring system based virtual learning environments. Most of these virtual learning systems focus on tutor activity and use artificial intelligence techniques. Information about the interaction with these systems is used to create a model that, given the preferences and learning styles of a student, performs an information retrieval process to adapt content delivery to the student, according to his/her particular characteristics (learning style, behavior, performance, and whether the student has a disability or not).