Research has always had a wide impact on society, but this does not always come in the form of a clearly defined outcome, application, or effect. It frequently occurs as a more gradual development in the understanding of the consequences of new knowledge. It may also happen long after the corresponding research was done, or be the outcome of repeated interactions between research and society. This can make societal impact difficult or impossible to trace back and attribute to the specific research from which it originated. In addition, that research may have already been evaluated without this impact having been taken into account.