There are two different types of Mediumship, Mental Mediumship and Physical Mediumship. Mental Mediumship occurs when the only person that is aware of the Spirit Communication is the Psychic Medium.
This occurs when you experience any of the 8 Clair Senses:
Clairaudience-Clear Psychic Hearing
Clairvoyance-Clear Psychic Seeing
Claircognizance-Clear Psychic Knowing
Clairsentience-Clear Psychic Physical Feeling
Clairempathy (Empathic)-Clear Psychic Emotional Feeling
Clairtangency-Clear Psychic Touching
Clairgustance-Clear Psychic Tasting
Clairsalience-Clear Psychic Smelling
Physical Mediumship occurs when Spirit Communication is visible to more than just the Psychic Medium. This occurs when a Spirit or Entity takes over the Psychic Medium's body, using it as a vessel. Throughout this guide you will learn about Mental Mediumship.
You may have heard of Hans Holtzer, he was a renowned Paranormal Investigator who worked with several Psychics that practiced Physical Mediumship. He most frequently teamed up with Ethel Johnson Meyers. If you haven't heard of Ethel you should take some time to watch her on YouTube. Physical Mediumship is interesting to watch, however, when practicing it the Psychic Medium is vulnerable to negative entities. There are only a small number of Psychic Mediums in the world today that intentionally practice Physical Mediumship. Mental Mediumship occurs more frequently and is overall safer to practice. Throughout this guide I will simply refer to Mental Mediumship as Mediumship.