When one is talking about mediums with an artist then it means that they are talking about the different types of artist materials and supplies that they use for creating their art. The technical explanation of what an art medium is comes down to whatever will make a mark upon a surface.
The most common types of mediums are those used for drawing and painting. For the artists that are into painting, they will often favor either the acrylics or the water colors. For those that are into drawing they have a wider range of mediums that they may use, which can be colored pencils, pastels, or inks and of course standard pencils. Then there are artists that really like to specialize in using mixed media as it allows them to be more creative, and often takes away the sense of boredom that can come with staying within the one medium range.
The one thing about mediums is that they are each unique in their own realm and have their own characteristics. It allows the artist to develop their techniques for creating the art that they favor the most. One other type of medium that is used is oil paints, however the techniques used for this are quite different than the other mediums.
For the new artists that are trying to decide where their real talents lie, they will often test the different mediums with the techniques that they are the most comfortable with. Based on the end results of this it will help to lead them as to what medium they want to work with the most. As with any product they must purchase products of quality if they are going to get the desired results that they are looking for.
Often what becomes a point of contention with artists is that as they are new and breaking into the industry finances are very tight, and it is difficult for them to be able to invest in the top quality mediums that they would really like to use.