When sharing data, it is important to consider how you want your data to be reused. You can then apply a relevant licence that most closely depicts those intended uses. Applying an explicit licence removes any ambiguity over what users can and cannot do with your data.
Lawyers can craft licences to meet specific criteria, but there are a number of open licences developed for widespread use on the internet that anyone can apply. Different types of subject matter necessitate differences in licensing. Licenses designed for one type of subject matter aren’t always best suited to licensing another type of subject matter because of differences in how copyright law applies Creative Commons (CC) licences were designed for 'generic' digital content and as such aren’t always best suited to licensing specific types of subject matter which engender different intellectual property rights. Indeed Creative Commons themselves have recommended against using their licences (other than CC Zero - CC0, or 'no rights reserved') for data and databases.
The Open Knowledge Foundation's (OKF) definition of 'open knowledge' says that knowledge is open if 'one is free to use, reuse, and redistribute it without legal, social or technological restriction.'
Similarly, the Panton Principles for Open Data in Science state that 'for science to effectively function, and for society to reap the full benefits from scientific endeavours, it is crucial that science data be made open.'
For further information see:
The DCC's guide on How to License Research Data. This guide will help you decide how to apply a licence to your research data, and which licence would be most suitable. It should provide you with an awareness of why licensing data is important, the impact licences have on future research, and the potential pitfalls to avoid. It concentrates on the UK context, though some aspects apply internationally; it does not, however, provide legal advice. The guide should interest both the principal investigators and researchers responsible for the data, and those who provide access to them through a data centre, repository or archive.