army navy	Find records that contain at least one of the two words
+army +navy	Find records that contain both words.
+army marines	Find records that contain the word army, but rank records higher if they also contain marines.
+army -marines	Find records that contain the word army but not marines.
arm*	Find records that contain words such as army, armed or Armistice.
"air force"	Find records that contain the exact phrase air force.