The Spotlight searching system in OS X is not only good for finding files, but because it includes applications and access to services like the dictionary on the system it can be useful as an application launcher, and a quick dictionary reference, among other uses. All of these can be accessed from any application by pressing Command-Space or selecting the Spotlight menu in the menu bar, and then entering a search query.
If you use Spotlight for these additional features, then you might consider optimizing these functions by organizing how Spotlight locates search results. For instance, if you regularly use Spotlight as an application launcher and enter TextEdit as the search term, then you might prefer to have located applications appear above other search results, to make them easier to navigate to an open with a few arrow presses and a hit of the return key.
To make any category show above others, simply move it up in the list. Move relatively unused ones higher up to give them priority when you need to search for that content.
This organization can be done in the Spotlight system preferences, where in the Search Results tab you can drag the various categories around to have the preferred items show at the top of the list. If you always search for applications, then consider moving this category to the top of the list.
While such changes might seem obvious, optimally organizing Spotlight may not be as intuitive as it seems. For example, since searching for contacts might not always be your uses for Spotlight, you might think to move this category to the bottom of the Search Results list; however, by doing so, on the rare occasion that you are searching for contacts then you will find them always positioned at the bottom.
With this in mind, it might make better sense to put the Contacts category at the top of the Spotlight organization list at the first or second positions. In this configuration, when contact information is not part of a search then this category will simply not show, but when you are searching for contacts then they will be located toward the top of the Spotlight search results.
Optimizing spotlight in this manner will take some trial and adjustment to suit your specific needs, but when done can greatly enhance its usefulness as a means for accessing what you want in the system.