UCD is a probably the dominant design methodology in the design of interfaces and systems. First defined by D. Norman in 1998, Normal itself present an alternative to the model named Activity Centered Design.
In this presentation you will find the basic concepts of UCD: What it is? (philosophy and principles), How to use it? (methodology and basic tools) and finally, point some alternatives to UCD method as: Activity Centered Design (ACD) or Goal Directed Design developed by Alan Cooper.