This symbol takes its name from the island nation of Malta in the southern Mediterranean Sea, which it has been associated with since the 16th century and of where a version of the symbol appears on the national flag.
The cross itself, however, carried significant meaning for hundreds of years before it traveled to this tiny island. During the Crusades (c. 11th-13th centuries), it was the symbol of a prominent military and religious order; The Knights of the Order of St. John of Jerusalem. Also known as the Knights Hospitallers, this brotherhood was one of the most famous organizations of the European Middle Ages. Essentially a group of ‘military monks’, they fulfilled duties both as physicians on the battlefield and established hospices and other centers to care for Christian pilgrims visiting the Holy Land.
The eight points of the Maltese Cross have been assigned various symbolic associations over the years, typically religious in nature and relating to proper conduct in life. One of these sets of associations is as follows (courtesy of http://www.guidetomalta.net/):
In modern times, this cross has seen wide use as an emblem for general humanitarian causes, and variations of the symbol can be found in the imagery of organizations such hospitals and law enforcement, as well as fire and police departments.