This section contains descriptions of server settings that cannot be changed at the session or query level.
These settings are stored in the `config.xml` file on the ClickHouse server.
Other settings are described in the "[Settings](../settings/index.md#settings)" section.
Before studying the settings, read the [Configuration files](../configuration_files.md#configuration_files) section and note the use of substitutions (the `incl` and `optional` attributes).
