The alto saxophone is a single-reed wind instrument, usually pitched in E-flat, combining an expressive middle register with melodic agility. In Mexico it appears in wind bands, jazz groups, dance orchestras, and contemporary-music projects. It may join arranged horn sections or take a solo role shaped by phrasing, articulation, and improvisation. This category makes it possible to explore its presence across recordings from different periods and settings. When describing a particular record, it is useful to establish whether the part was written, improvised, or developed through collective practice within the ensemble.