What Does Open Data Mean?
Open data is the notion that certain types of data should be freely available for everyone to use and share without restrictions such as copyrights, patents or other control mechanisms. The only requirement - at most - is that those who use and share the data attribute it to its source. Open data supporters believe that some types of data contribute to the common good or should belong to everyone because they were gathered using public money.
Techopedia Explains Open Data
Open data is often focused on material related to science, medicine, maps, chemical compounds and other data that may contribute to the common good. Of course, much of the data also has commercial value, which drives those who discover it to prevent it from being open source.