When does a search occur? When can private parties be considered government actors? What is a seizure?

When does the Fourth Amendment apply?
How is the fourth amendment best analyzed?
When does a search occur?
When can private parties be considered government actors?
What is a seizure?
Distinguish between seizures of persons and seizures of property.
What is justification and why is it important?
Compare and contrast probable cause, reasonable suspicion, and administrative justification.