NESH's Guidelines stipulate that researchers must treat all information about private matters confidentially. The material must usually be anonymised to protect privacy and to prevent harm and a severe burden on the persons being researched (point 14).

Internet research is often based on interaction in digital forums (Twitter, Facebook, blogs, etc.), which is of an ephemeral nature, contributing to the expectation that the information is protected. In such situations, people may be willing to volunteer personal and sensitive information in an Internet forum that in principle is available to all people, without intending for the statements to be shared or studied (points 17 and 18). When a person's personal or sensitive data is available in an open forum and it is used for research purposes, they are entitled to the data being used and communicated appropriately (point 13).

The purpose of anonymity is to protect an individual's privacy, so that the information is treated properly and identifiable data is processed by as few people as possible.

Pseudonyms ("'nicks" or nicknames) are an important aspect of certain forms of interaction on the Internet. Pseudonyms are often used on different forums and in different contexts. Researchers should take into consideration that the use of the subjects' pseudonyms does not necessarily mean that their personal data is anonymised.

Big Data raises a whole set of new problems and challenges. Everyone leaves vast quantities of digital data – whether we use social media, swipe our cards, use our phones, buy apps or search the Internet – all of which can potentially be linked by researchers (or others) in ways the individual has no knowledge of or has granted informed consent to. It is also easier to track the informants' identity when they use digital forums than when they use other information channels. One might go as far as saying that linking Big Data and tracking IP addresses makes the concept of "anonymity" impossible in practice. Researchers may find it difficult to guarantee both that the data is, in fact, anonymous and that personal data will be deleted after the research project. Nevertheless, doing so is the researcher's responsibility. Potential informants must be informed as far as possible about these challenges and the possible consequences of the research. This is particularly true when the research leads to information being linked and generating new, sensitive information about identifiable individuals.