The quick-and-simple explanation of Spirit Guides!
1) Spirits. So they are typically ancestors, angels, animals, faeries, ascended masters, earth spirits (you get the idea- they run the gamut). They are in Spirit, which means they are not in physical form.
and they are…
2) Guides. Chosen by us before being incarnated, for the express purpose of supporting us and guiding us as we navigate this lifetime.
They are often Spirits with whom we have spent previous lifetimes, so they know us well. They have gained a lot of wisdom in some area of life that we plan to explore.
Everyone has guides, usually at least three, and as many as a dozen or more. It really depends on what you chose before you came into your physical body. Some guides stay with us for our entire life, some come and go, depending on what challenge we are faced with and how they have agreed to help.
Mediums talk to your guides and deceased loved ones to deliver important messages, and to help you get guidance.
Side Note: It’s my personal belief that when I do a tarot reading, one or more of your guides show up to make sure the right cards come out. I believe this because I sense their presence. However, this is not the same as a Mediumship reading. The main difference being, I don’t expend the energy to identify the Spirit speaker when I do a tarot reading, and I use a physical tool to grab the message, vs. relying 100% on Spirit-Communication (in mediumship) to receive the message.
Another Side Note: I also think that if a reader wants God/Source/The Universe to guide the reading, then that’s what they tap into. If they want the Higher Self of the person they’re reading for to guide the reading, then that’s who they tap into. If they want science and random chance to dictate how the cards fall, then that is how it goes.