Before creating or collecting data it is worth first checking whether there is pre-existing data you can use. This can save resource and avoid a number of issues if someone else has been helpful enough to create what you need and allow you to re-use it.
If pre-existing data exists, you need to check the terms of any license terms for re-use of the data and/or the conditions applied to it's use. For creative works and data the most common type of license is a Creative Commons license, but code or software may be available under an Open Source License.
If there is no description of permissions or license attached to the data, you may need to contact the copyright/data owner to ascertain if you can use it and under what conditions. Ensure you have consent to re-use and share the data (in case it is requested in peer review, for example).
You will need to factor whatever license or permissions that apply to the data into your plans for dissemination of the work or sharing of any derivative data. E.G. If the data is licensed for non-commercial purposes, you may not be able to sell work resulting from it. Some licenses may also be incompatible with others, causing issues when merging data.
You may find information on how the data should be cited from the repository record where the data is located. If this doesn't exist, you may wish to use Data Cite's DOI Citation Formatter to generate a citation in a specific style using the DOI of a dataset.
If you need to collect or create new data and/or identify issues around intellectual property/ownership, ethics, funder requirements or costs, explore the links below for more information on these areas.