Many apps include a search field where you can type to find something that the app knows about. With Spotlight Search, you can search all the apps at once.
Search iPod touch. Drag down the middle of any Home screen to reveal the search field. Results occur as you type; to hide the keyboard and see more results on the screen, tap Search. Tap an item in the list to open it.
You can also use Spotlight Search to find and open apps.
Choose which apps and content are searched. Go to Settings > General > Spotlight Search. You can also change the search order.