Open Licenses for sharing your work by Jonah McAllister-Erickson is licensed under CC BY 4.0
In the United States, facts by themselves are not protected by Copyright and most other forms of Intellectual Property. Therefore data that is just a collection of facts is not protectable by U.S. Copyright law. In the U.S. databases as a whole can be protected as a compilation, but that only provides limited protections, and only for the arrangement and selection of factual data.
In the European Union, the databases are projected by the Database Directive. This act gives additional protections both under copyright and under sui generis (of its own kind) database rights, which protect the time and investment in collecting and verifying the contents of databases. The act restricts:
Data of course can be more than merely factual in nature, for example microscopy images, field notes, photographs, survey data may all be protectable to some degree by Copyright.
Because legal protection for data varies by nature of the data and the national jurisdiction, it is created and accessed in licensing your data can be important. Leaving your dataset unlicensed creates uncertainty about the use and re-use of your data. Licensing your data explicitly states that your data is open for re-use.
In the U.S. if you want to ensure maximum usability for your data, you can apply a Creative Commons Zero (CC0) license to openly share your dataset worldwide. Creative Commons Zero (CC0) functions as both a waiver and a license. It is intended for dedicating works to the public domain by waiving all copyrights in the work. However, in jurisdictions were that is not allowed, it also functions as a irrevocable, royalty-free, and unconditional license for anyone to use the work for any purpose. You can find additional information about using the CC0 license for data on the Creative Commons wiki.
The Open Knowledge Foundation, Open Data Commons provides three data licenses that are similar Creative Commons licenses. The advantage of the Open Data Commons licenses is that they have been specifically written by creators and users of data.
Open Data Commons Open Database License (ODbL)
Permits others to:
So long as the they:
This license is very similar to the CC-BY-SA license discussed elsewhere
The Open Data Commons Attribution License
Permits others to:
So long as provide attribution.
Attribute: You must attribute any public use of the database, or works produced from the database, in the manner specified in the license. For any use or redistribution of the database, or works produced from it, you must make clear to others the license of the database and keep intact any notices on the original database.
This license is like the CC-BY license
Open Data Commons Public Domain Dedication and License (PDDL)
Permits others to
Without any other restrictions. Functionally it is the same as the CC0 license and the two can be used interchangeable.