A summary of my understanding of activity theory and its potential for describing activity systems. An activity is the minimal meaningful context to understand individual actions.
First off, broadly defined, Activity Theory is a philosophical and cross-disciplinary framework for studying different forms of human practices as development processes, both individual and social levels interlinked at the same time. According to the article by K. Kuuti ((1995). Activity theory as a potential framework for human-computer interaction research. In. B. Nardi (Ed.), Context and Consciousness: Activity Theory and Human Computer Interaction. Cambridge: MIT Press), the activity theory has three main characteristics: Activities are basic units of analysis, activities develope and activities always contain various artifacts.
To follow these characteristics and especially the first one, then activities, which make up the whole process, have a certain structure. Since there are various artifacts in play than two possibilities have been brought out. Firstly the basic structure of mediated relationship at an individual level, which contains the relation between the subject, the object and the tool. These three combined, go through a transfomation process and produce an outcome. This outcome is ,however, too simple to fulfil the needs of a consideration of the systemic relations between an individual and his environment in an activity. So to complement the activity structure, one must add rules, the community and the division of labour into the formula.
The main thing to bear in mind is that the activity theory can be used to conceptualize and assist in the development of processes and different activities. We can try and utilize the analysis outcomes within a human driven process, to help us prevent mistakes, offsets. Also there is a possibility to use the information to outperform human actors/factors in a process or even skip them completely if it makes the process or activity better. But, as it is also stated in the article by K. Kuuti, we must keep in mind the evolvement of activities and considering the cost of improvements, it might be often better to let the human factor develope.