Search finds nothing

I have installed my first search box, and all I ever get is "Your search yielded no results".

There must be some underdocumented dependency that I have not fulfilled.

• Is Drupal Search using Google? Because this is a development site not on the Internet, so google of course can not find it.

• Does it depend on Taxonomy? Because I have not implemented any taxonomy.

• Does it depend on the cron job? Being a transient development site, I never run the cron job.

In "Modules / CORE" I enabled "Search", but others such as Taxonomy are not enabled. Search doesn't say anything about being dependent on anything else.

I have searched Drupal.org for documentation on the core "Search" functionality and can not find any. Special searches, extended facilitiess, yes, but not the core.

(A few months ago I discovered the hard way that Drupal's e-mail feature depends on sendmail being installed - an undocumented dependency. I have not trusted Drupal documentation since then.)

So why can't my search box find anything?