is_multisite()

If Multisite is enabled.

Return

(bool) True if Multisite is enabled, false otherwise.

Source

File: wp-includes/load.php 

function is_multisite() {
	if ( defined( 'MULTISITE' ) )
		return MULTISITE;

	if ( defined( 'SUBDOMAIN_INSTALL' ) || defined( 'VHOST' ) || defined( 'SUNRISE' ) )
		return true;

	return false;
}

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Changelog

Changelog
Version Description
3.0.0 Introduced.