Spotlight is the superfast search technology that Apple introduced in Mac OS X 10.4. With Spotlight, you can search all files on your hard drives and search results will appear instantaneously. You can set a few preferences for Spotlight by first opening the Mac OS X System Preferences and then clicking on the Spotlight button.
You can narrow the results of your searches to just certain types of files. Select the Search Results tab on the Spotlight preferences pane and you'll see a long list of file types in the center of the pane.

Put a check in the box in front of any file types you want included in your searches. Spotlight will display the search results according to the order of the types in the list, but you can reorder the types by dragging any type up or down in the list.
You can use keyboard shortcuts to show either the Spotlight text box from the menu bar or to use Spotlight in the Finder. To set keyboard shortcuts for Spotlight, put a check in the box(es) in front of the option(s) you want (Spotlight menu keyboard shortcut and/or Spotlight window keyboard shortcut) on the Spotlight preferences pane, click the arrow next to the option and select the keyboard shortcut you want from the drop-down menu.
There might be some files, folders or drives you never want to search. To prevent Spotlight from searching in those locations, select the Privacy tab on the Spotlight Preferences Pane.

Next, click the plus symbol on the left side under the pane. A Finder pane will open and you can locate and select a file, folder or drive to exclude from all searches.