# Handling Time

By default, all datetime values returned by the API are in UTC. The API provides `start_time` and `end_time` query parameters to filter results based on a specific time range. These parameters only filter on a dataset's `time_index_column`. If a dataset does not have a `time_index_column`, these parameters do not apply.

* `start_time`: Specifies the start of the time range for the query. Records with a timestamp equal to or greater than the `start_time` will be returned. Format: `YYYY-MM-DDTHH:MM-HH:MM`
* `end_time`: Specifies the end of the time range for the query. The `end_time` is not included. Records with a timestamp less than the `end_time` will be returned. Format: `YYYY-MM-DDTHH:MM-HH:MM`

A few notes about how datetime parameters are handled:

* If no `start_time` or `end_time` are specified, the API will return all records
* If no timezone or offset is specified, the API defaults to using UTC. For example, `2021-01-01T00:00` is equivalent to `2021-01-01T00:00+00:00`.
* If only a date is provided without a time, it is assumed to be 00:00 of that day. For example, `2021-01-01` is equivalent to `2021-01-01T00:00+00:00`.
* You can provide a timezone offset in the format `+HH:MM` or `-HH:MM`. For example, `2021-01-01T00:00-05:00` is equivalent to `2021-01-01T05:00+00:00`.

Examples of valid time strings:

* `2021-01-01T00:00+00:00`
* `2021-01-01T00:00-05:00`
* `2021-01-01T00:00`
* `2021-01-01`


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