Being the gateway to the encyclopedia - the Main Page is Wikipedia's most frequently visited page. The main page is always protected and can only be edited by admins. But, most of the content on the main page is piped in each day from various departments, via templates. The volunteers in these departments work year round to prepare the content on the Main Page to be viewed by the World each day.
The departments that prep content for the Main Page are:
Anybody can help prep the pages that feed into the main page's templates (up until the day they are displayed on the Main Page), by proofreading and correcting them, and we encourage you to do so. (continued tomorrow)
Read more:
Wikipedia:Editing the main page