Qualia are the subjective, conscious experiences of the world, such as the taste of coffee, the smell of roses, or the feeling of pain.

Thomas Nagel is a contemporary philosopher who is known for his work on qualia and consciousness. His famous essay 'What Is It Like to Be a Bat?' explores the idea that subjective conscious experiences cannot be fully understood by an external observer.

The hard problem of consciousness is the challenge of explaining how subjective conscious experiences arise from physical processes in the brain. It is considered to be one of the most difficult problems in philosophy and science.

The knowledge argument states that qualia are necessary for knowledge of the external world because they provide us with direct access to our own subjective experiences. Without qualia, we would not be able to know anything about the world around us.

The inverted spectrum thought experiment is a thought experiment that asks whether it is possible for two people to have the same qualia but with different physical stimuli. For example, one person might see the color red when looking at a rose, while another person might see the color green when looking at the same rose. The experiment is used to argue that qualia are subjective and cannot be reduced to physical properties.

The self in the context of qualia is the unified subject of consciousness that experiences qualia. It is the 'I' that has conscious experiences and is aware of its own existence.

The problem of other minds is the problem of how we can know that other people have qualia. Since we can only directly access our own qualia, it is difficult to know for sure whether other people have the same qualia that we do.

The simulation theory of consciousness is the theory that consciousness is a computer simulation that is run by a powerful computer. This theory is based on the idea that consciousness is a computational process that can be simulated on a computer.

Panpsychism is the theory that consciousness is a property of all matter. This theory is based on the idea that consciousness is a fundamental property of the universe and that it is not limited to living things or complex systems.

The integrated information theory of consciousness is the theory that consciousness is a product of the integration of information in the brain. This theory is based on the idea that consciousness is an emergent property of complex systems and that it arises from the interactions between different parts of the brain.