The evolution from Computer-Aided Instruction (CAI) to Intelligent Computer-Aided Instruction (ICAI) was the first step by which education and artificial intelligence communities began to look at each other's work. This text looks at the evolution toward Intelligent Tutoring Systems (ITS) which can be thought of as a step beyond ICAI, leading to more classes of problems and approaches. ITS involves artificial intelligence concepts approaches, dynamic student modelling, human cognition, intelligent user interfaces, intelligent help systems and the use of strategies.