Data is something you can collect, create, or generate during your thesis project. Before you start your thesis, make a list for yourself and describe at least the different types of data, amount, and format, e.g.:
During data collection, the information can and is allowed to change.
If you handle data that contains confidential or personal information, you must take confidentiality issues into account. Read more under the section Confidential information and personal data.
Do you need specific tools for data collection and analysis? Discuss with your supervisor what these might be, and how you can access them.
Note that you can also reuse data that someone else has collected and opened for others to use. You can find such data in databases, archives, and repositories or data archives. If you want to open your data yourself when your thesis is finished, you can do so in a repository. Read more about repositories in this guide under the heading What happens to the data after the project?