Collaboration theory, suggested as a system of analysis for CSCL by Gerry Stahl in 2002-2006, postulates that knowledge is constructed in social interactions such as discourse. The theory suggests that learning is not a matter of accepting fixed facts, but is the dynamic, on-going, and evolving result of complex interactions primarily taking place within communities of people. It also emphasizes that collaborative learning is a process of constructing meaning and that meaning creation most often takes place and can be observed at the group unit of analysis. The goal of collaboration theory is to develop an understanding of how meaning is collaboratively constructed, preserved, and re-learned through the media of language and artifacts in group interaction. There are four crucial themes in collaboration theory: collaborative knowledge building (which is seen as a more concrete term than "learning"); group and personal perspectives intertwining to create group understanding; mediation by artifacts (or the use of resources which learners can share or imprint meaning on); and interaction analysis using captured examples that can be analyzed as proof that the knowledge building occurred.