  Data providers such as government statistical agencies perform a balancing
act: maximising information published to inform decision-making and research,
while simultaneously protecting privacy. The emergence of identified
administrative datasets with the potential for sharing (and thus linking)
offers huge potential benefits but significant additional risks. This article
introduces the principles and methods of linking data across different sources
and points in time, focusing on potential areas of risk. We then consider
confidentiality risk, focusing in particular on the "intruder" problem central
to the area, and looking at both risks from data producer outputs and from the
release of micro-data for further analysis. Finally, we briefly consider
potential solutions to micro-data release, both the statistical solutions
considered in other contributed articles and non-statistical solutions.
