ClickHouse stores date and time values in the Unix timestamp format that is independent of the time zones and daylight saving rules. The time zone value affects displaying `DateTime` values in text formats and parsing the input strings for storage. You can find the list of supported time zones in [IANA Time Zone Database](https://www.iana.org/time-zones).
You can explicitly set a time zone for `DateTime`-type column when creating a table. If time zone isn't set, ClickHouse uses the value of the [timezone](../operations/server_settings/settings.md#server_settings-timezone) server configuration parameter or the operating system settings at the moment of the ClickHouse server start.
The [clickhouse-client](../interfaces/cli.md) applies the server time zone by default if a time zone isn't explicitly defined when initializing the data type. To use the client time zone, run it with the `--use_client_time_zone` parameter.
ClickHouse outputs values in the `YYYY-MM-DD hh:mm:ss` text format by default. You can change the format with the [formatDateTime](../query_language/functions/date_time_functions.md#formatdatetime) function.
When inserting data into ClickHouse, you can use different formats of date and time strings, depending on the [date_time_input_format](../operations/settings/settings.md#settings-date_time_input_format) setting value.