Lifetime dates and workflow settings globally control which items are visible at various times. The most recent version of each language which has no publishing date, is not scheduled for future publication, does not have the Never publish checkbox selected in the Publishing section and in the Lifetime section has null dates or dates which surround the system date will be published. If an item’s parent is not published, then the item itself is not published - http://localhost/Company/AboutUs.html cannot exist without /company. Publishing can be further restricted to specific languages and/or publishing targets. With Sitecore the term Publish means to copy appropriate versions or entire items from the master to the web database accounting for these settings. See:
The frequency of scheduled publication can be manipulated, but note that publishing clears the HTML cache and therefore can interfere with performance. Review http://sdn.sitecore.net/SDN5/FAQ/Administration/Scheduled%20tasks.html and manipulate the Sitecore.Tasks.PublishAgent which is by default disabled by comments /web.config. Multiple entries may be required to support multiple languages.