A page's background and the website background underneath the page itself comprise a deciding factor in determining a visitor's perception of your site.
A website background spans the entire width of the browser window, while a page background can be used to back only the content of the page itself. Often, a simple two-color top-to-bottom graident spans the height of the average computer screen (usually about 1000 pixels). The lower part of the background after the color transition is often colored in a way that allows it to stretch further down for pages more than 1000 pixels in height.
In the example below, the grapevine website background creates an Italian vineyard atmosphere.