Open data

Open data is data made available for people to access, use, and reuse under clear terms. Useful open data comes in a format that can be processed, with documentation explaining its contents and limits. A public-safety dataset can be open while still excluding information that is protected or unsuitable for public release.

Reuse requires more than a visible chart

Federal open-data principles emphasize accessible, machine-readable formats, descriptive documentation, and open licensing, subject to valid privacy and other restrictions. “Machine-readable” means the information is structured so software can process it, such as a table with separate fields. Resources.data.gov open-data principles.

A chart helps people see a result. An accompanying downloadable dataset allows them to inspect records, reproduce a calculation, or ask a different question. Those uses require field definitions and a clear statement of what the file includes.

Example

Hypothetical: A city publishes monthly call totals as an image and also provides a downloadable table with month, call category, and count fields. The table includes definitions, an update date, and reuse terms.

The image communicates the pattern; the table supports independent analysis. If the city excludes sensitive call categories, that exclusion remains part of the data's scope. A user cannot describe the download as every call merely because it is openly available.

Common confusion

Open data and public records are related but different concepts. A public-records law concerns access to government records under applicable rules. An open-data release is a particular published resource, often prepared for broader reuse. It may contain selected fields or summaries rather than the full original documents.

Open data is also not automatically verified for every possible use. A file can be accessible while containing missing values, later revisions, or local coding that requires interpretation. Openness makes inspection possible; it does not replace the inspection.

What makes a release useful

Look for the source organization, license or reuse terms, update process, field dictionary, geographic coverage, and period represented. An explanation of excluded records is as important as the list of included fields.

When reusing data, preserve the source and extraction date. If categories are combined or records removed, describe those processing steps so a reader can distinguish the publisher's release from the resulting analysis.

A download link that works today may provide a revised file tomorrow. Keeping a version reference or dated copy helps explain why two analyses of the same period can differ without either using a different underlying question.

Related terms

• Public record
• Metadata
• Data dictionary
• Data quality

Sources

• Resources.data.gov: Open Data Principles — Federal guidance on accessibility, documentation, reuse, timing, and lawful restrictions; not a claim that every local portal meets those principles.