includes: Contains a large number of inc files, which store commonly used functions in Drupal
misc: stores js available in drupal installation,
imagemodules: stores the core modules of drupal (actually there are only 5 real core modules of drupal)
profiles: Installation outline of the site
scripts: stores a large number of script files
sites: Contains the modifications you have made to drupal
themes: stores drupal’s default theme and template engine corn.php: performs periodic tasks
index.php: starting point for drupal operation
istall.php: drupal installation entrance
update.php: Update drupal database
xmlrpc: Accept XML_RPC requests robots.text: Default implementation of search engine crawler exclusion criteria