What is the concept of ontological idealism and how does it differ from other philosophical perspectives on reality?

Ontological idealism is the belief that reality is fundamentally mental or spiritual in nature, rather than physical. This perspective holds that the mind or consciousness is the primary reality, and that the physical world is dependent on mental processes. This differs from other philosophical perspectives, such as materialism, which assert that the physical world is the ultimate reality, and dualism, which posits a separation between the mind and body.