I'm a bit confused about the presence of a static friction FORCE. So here's the question: The potential for static friction is always present due to the nature of the contact surfaces and the normal force. But is a static friction FORCE always present or does it arise in response to (specifically in opposition to) the application of some force, somewhat like normal force? The reason I'm wondering is that it seems to me that if static friction is constantly present as a force it would cause some acceleration in some direction. Which direction would it be? Thanks for the help!