The EU Open Data Portal offers, a free, single point of access to a wide range of data held by EU Institutions and bodies. In general you can reuse data free of charge, for commercial or non-commercial purposes, provided you acknowledge the source.
One of the advantages of this portal is that it enables you to link data from various sources automatically that can then be used in a new and creative way.
Useful leaflets about the EU Open Data Portal are available from the EU Bookshop: EU open data portal: The data hub of the European Union and Unleash the potential of your data with the EU open data portal.
Here’s a short explanatory video from the European Commission:
And you can click on the image below to have a look at an example of Open Data Portal reuse.