Data as opposed to software or hardware, has been a contributing factor in many accidents and incidents. However, data in safety related systems is not sufficiently addressed by current safety management practices and standards. There are clear business and societal benefits in terms of reduced harm, reduced commercial liabilities and improved business efficiencies, in investigating and addressing outstanding challenges related to the safety of data. This book provides clear guidance on how data should be managed in a safety-related context. This work is by the Data Safety Initiative Working Group (DSIWG) - a cross-sector industry working group set up to address the challenges of data safety.