A Medium connects to discarnate spirits in the other dimensions, whether they be deceased loved ones, and ,spirit guides in the 4th dimension nearest to us or angels in the 5th dimension and above or even extra-terrestrials. The confusion often comes with the mixup between the words Medium and Clairvoyant.  Clairvoyance is the HOW. It is ONE of the ways a Medium may work. Someone who is Clairvoyant may not be a Medium and a Medium may not be Clairvoyant.  Each Medium will work differently. 

The Three Levels of Mediumship

Mental mediumship

This is what most Mediums. This means the Medium is working with a Spirit Guide and the Spirits of departed loved ones. Your own Spirit Guide will allow other Spirits to come forward and give you messages from friends and family who have passed over. People who have passed are closer to us in the third dimension so it is easier for them to communicate.  They don't usually know any more about your life than you do but they do bring messages of comfort.  Your Spirit Guides are older souls who have agreed this lifetimes lessons with you and will guide you.  They often use a Medium to communicate with you if you are not listening to your own inner guidance which is how they communicate directly with you. 

Overshadowing

Is when a Spirit comes particularly close and can be seen on the Medium’s face. It is like they project their own features onto the face of the medium thus allowing others to see them. This takes much more energy both from the Medium and the Spirit.  THey are usually older soul's and guides.  They give messages directly but do not take possession of the Medium. The Medium needs to be very relaxed and open to allow a Guide that close.

Trance mediumship

This is where the Spirit will enter the Medium’s body (usually from the back) and possess the Medium. This is where the Medium’s voice and mannerisms will take on those of the Spirit who is giving the message. Often known nowadays as ‘channelling’. There are also various levels of trance from very light to a deep hypnosis type state. A Medium only usually gives messages from one particular Spirit Guide.  

Whatever mediumistic abilities are developed over time, some will have more affinity to one or other level of mediumship.  They will either specialize in bringing messages from passed over loved ones, whilst others will work more closely with spirit guides and angels. How a Medium receives the information is via the Six “Clairs” commonly referred to as Clairvoyance. (See Here for how it is done). https://joylina.com/knowledgebase/divinations/clairvoyance