
A DOI, or Digital Object Identifier, is a persistent identifier which aims to perpetually resolve to an information object. The objects can be an online article, research document, journal article, and even a dataset. Here is an example of a DOI:10.1000/182. This URL will resolve to the object https://doi.org/10.1000/182. Adding a DOI to you dataset will help readers locate it now and in the future.
For datasets, the Figshare, Zenodo, and Dryad repositories will provide a DOI for uploaded works. In addition, there may be a domain-specific repository in your field which provides a DOI for datasets. The journal Scientific Data maintains a good list of repositories you can look at.