Open data refers to the open access and free use of data. It therefore stands in contrast to the propriety method, which heavily restricts the reuse and further use of data. This openness relates to things like teaching materials, geodata, traffic information, academic publications and the results of medical research. Supporters promote the principle that positive developments for the general public can only be achieved through freely available data. Open data can make a valuable contribution to greater transparency and enable committed citizens to participate and work together. The adaptation of the copyright and patent law to the new internet culture of free exchange has lent political relevance to the “open movement”.