# Observation date

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**Observation date:** The date we read a value from its public source.

## How we measure it

Every row carries it. A dataset's freshness is the age of its newest observation date.

## What it is not

It is not the date a page was built or the date a sale happened; sale rows carry their own sale date.

## Where it appears in the data

Field names as the API returns them; each dataset's page in the API lists the field's type and unit.

- `observed_date` in dataset `airbnb_depth_observations`

## Related

- [Free reports: what we publish and hold back](/methodology/public-reports/)
- [All glossary terms](/glossary/)