At [DLMURL]http://ask.yahoo.com/20030324.html[/DLMURL] I found this definition which I thought was short and sweet.
What causes Stockholm Syndrome? Captives begin to identify with their captors initially as a defensive mechanism, out of fear of violence. Small acts of kindness by the captor are magnified, since finding perspective in a hostage situation is by definition impossible. Rescue attempts are also seen as a threat, since it's likely the captive would be injured during such attempts.
It's important to note that these symptoms occur under tremendous emotional and often physical duress. The behavior is considered a common survival strategy for victims of interpersonal abuse, and has been observed in battered spouses, abused children, prisoners of war, and concentration camp survivors.