How many points are required to define a plane?

1. Click to reveal two points P and Q;[br]2. Click for a plane on the line PQ;[br]3. Move the slider? How many planes go through two points;[br]4. Click to reveal a third point A;[br]5. Move the slider so that the orangle plane contains the three points P, Q and A;[br]6. Click to reveal plane that contains the three points P, Q and A;[br]How many points are needed to define a particular plane?
How many points are required to define a plane?
– Mark Willis

Information: How many points are required to define a plane?