Root Locus plots are a very useful way to predict the behavior of a closed loop system as some parameter of the system (typically a gain) is changed. This web page attempts to demystify the process. The various parts are more-or-less stand alone, so if you want to skip one or more, that should not be a problem. If you are only interested in a quick lesson on how to make root locus plots, examine part 3 in conjunction with part 5. A MatLab program designed to help learn to sketch Root Locus plots is described in part 6.
The documents are:
Documents 1-6 combined into one file (for easier printing).