Before participating in research, it is important that prospective participants consent to participate. When consenting, they need to know what they consent to: in other words, the consent has to be informed. This informed consent ensures that participation is voluntary, and that participants are aware that they can cease participating at any time without any negative consequences.
A second role of the informed consent relates to data sharing. There are many reasons why it is important to share the data researchers collect (see section 7.4), but researchers must never simply make all collected data public as a matter of course. There are a number of legal and ethical conditions that must be satisfied (Meyer 2018), and these differ for the three types of data participants can provide (personal data, creations, and facts; see section 7.4.1).
The simplest case concerns facts, which are a matter of public domain knowledge and as such cannot be owned by individuals or organisations. If you collect anonymous data (i.e. data that is not about specific individuals; i.e. is not identifiable, see section 8.1.1), you just have to make sure that your participants consent to provide data that will be made public.
However, sometimes, things are not that simple: collecting personal data may be inevitable, and/or your data may consist (partly) of creations. Personal data are owned by the corresponding person (see section 8.1), and can never be owned by other persons or by organisations: at most, personal data can be temporarily controlled and/or processed by other persons or organisations. If you collected personal data, you have to anonymize the data first (see 25). Creations are the intellectual property of their creator, until the creator decides to release them under a more permissive license than that default copyright license (see 8.2). Therefore, you have to make sure this license is clear.