Lecture #2 was an introduction to agents
If you want additional reading, try to track down
S. Franklin and A. Graesser, "Is it an agent, or just a program?: A taxonomy for autonomous agents", in Intelligent Agents III, Springer Verlag, LNAI1193, (J. P. Mueller, M. J. Wooldridge and N. R. Jennings, eds.), 1997.