Spotlight is a universal search box on iOS devices that makes it possible to quickly search for and find an app, contact, or e-mail directly from the home screen.
In previous versions of iOS, users would swipe to the left of the main home screen to access the search box. In iOS 7, as you may have already discovered, Spotlight is no longer located in the same spot.
Now, instead of swiping to the left of the main home screen, you can swipe down on any home screen to pull down the search field.
This is the same way users have previously found the search field in the Messages and Mail apps. After the initial shock of Spotlight being moved -- especially if you use it a lot (like me) -- you'll quickly adjust to the familiar gesture.
As for customizing what's searched and the order of results for Spotlight, that part has remained unchanged. Users can still access these settings by going to Settings > General > Spotlight Search.