What is Mixed Media?

Mixed Media is technically one piece of artwork that uses two or more art mediums.
This is often common among artists. Personally, I typically use more than two mediums. There are very few rules within mixed media
- and even those can be broken.
I've been creating art most of my life. My first mural was when I was four - all over my beautifully painted pink walls. I thought it would be lovely to my version of a wolf with permanent marker - one given to me and each of my kindergarten friends on a field trip to the Midway Airport. It was the '70's.
Fast forward over forty years later, and here I am creating but in different ways.
My BFA is in Fine Arts with an emphasis in Painting & Drawing. I was trained for years on how to paint with oils, acrylics, watercolors, and more.
Technique, composition, and practice were the primary focus, as they should be.
However, I like experimenting with materials and always have. This can be anything from all of the different types of paints like---
spray paint, acrylic paint, oil paint, milk paint, watercolor paint, interior & exterior paint.
Along with those materials, I'll add India ink, paint markers, oil pastels, pan pastels, pencil & pen.
I love to make my own alcohol inks and encaustic molds for those layers.
Adding any type of shiny texture is what brings me pure joy as it also satisfies my ADHD brain in glorious ways. Here are some examples of the above materials.

It is said that you can't ---or shouldn't use water-based with oil-based for obvious reasons. But there are ways around that.
Art is individual expression, experimentation, and perspective.
So, how can that be wrong?
No rules here.
Let's play.