Tagging systems represent the conceptual knowledge of a community. We experimentally tested whether people harness this collective knowledge when navigating through the Web. As a within-factor we manipulated people's prior knowledge (no knowledge vs. prior knowledge that was congruent/incongruent to the collective knowledge inherent in the tags). As between-factor we manipulated whether people had tag clouds available or not. In line with the Information Foraging Theory and with the Co-Evolution Model of individual learning and collective knowledge building, we found that people's prior knowledge and tag clouds influenced their navigation