Data License

Definition

A data license states what a recipient may do with a dataset or data feed: keep a copy, and for how long, compute derived results, publish them, or pass the data on to others. Having access to data does not by itself grant any of these rights.

In plain terms

“May I use this data?” is really several questions: may I read it, store it, for how long, derive results from it, publish those results, publish the rows themselves, use it commercially, hand it on? Different sources answer differently. Open licences such as Creative Commons or Open Data Commons grant many rights with conditions (for example attribution). Commercial feeds usually restrict storage and redistribution. A web page has its own terms.

The practical habit is to write the answers down for each source next to the data, to carry the restrictions into what you keep and what you export, and to record “not verified” honestly when you do not know. This page is general background, not legal advice.

Example

An invented feed, “Feed X”, and what its terms allow:

Consequences: raw copies must be deleted after 90 days, so results older than that can no longer be re-derived from the original; exports to others may contain aggregates only.

Common misunderstandings

• “If I paid for the data, I may do anything with it.” A purchase buys the rights written in the contract, which are often narrower than expected.
• “An open licence has no conditions.” Most require at least attribution, and some require sharing derived data under the same terms.
• “Public on the web means public domain.” Copyright and terms of use still apply to publicly visible pages.