Multisite

WordPress Multisite

# Network of sites from one installation
# Shared: plugins, themes, users
# Separate: DB tables (wp_2_posts, wp_3_posts)

# Enable in wp-config.php
define('WP_ALLOW_MULTISITE', true);

# After Network Setup (wp-config.php additions)
define('MULTISITE',            true);
define('SUBDOMAIN_INSTALL',    false); // subfolders
define('DOMAIN_CURRENT_SITE',  'example.com');
define('PATH_CURRENT_SITE',    '/');

# Site URLs
# Main:   example.com
# Site 2: example.com/site2/   (subfolder)
# Site 2: site2.example.com    (subdomain)

# Network Admin: example.com/wp-admin/network/

# Multisite functions
switch_to_blog($blog_id);
$sites = get_sites(['number' => 100]);
restore_current_blog();