Atmospheric music is normally used as a background in a visual presentation or speech. They are the types of music that are composed by talented musicians and are created in such a way that they are not distracting. They don't go in the way of the visual presentation at all. They are usually played in a loop along with a PowerPoint presentation or a video clip.
They are composed of relaxing notes to ease up the audience and put them in a harmonic mood. The results are usually better than not using any music for your presentations at all.