Data documentation ensures that your data can be understood, interpreted, found, and cited by any user. It is beneficial to use a metadata standard in order to ensure FAIR data, and to create a readme.txt file to ensure everything is documented and organized. It is also ideal to start the documentation process at the beginning of the research project, as it can be quite painful to complete afterwards.
Data documentation usually describes the content, formats, and internal relations of your data. Aspects of your data which should be documented, as described by DMPTool's guide to documentation, are as follows:
Readme.txt files are a valuable tool for documenting data, with a data dictionary being another good option. It is important that the readme.txt file describes the data and file overview as a whole, but also describes each individual dataset or file. It is imperative to have a variable list of column headings for tabular data.
This chart, created by the Cambridge Crystallographic Data Centre (CCDC), shows the importance of metadata when it comes to ensuring your data is FAIR.
FAIRsharing.org is a curated, informative and educational resource on data and metadata standards, inter-related to databases and data policies. FAIRsharing.org has information on more than 1600 standards, 1900 databases, and 150 policies.