A music stand is something musicians can use to put sheet music on when they are performing.
There are several different sorts of music stand, but almost all of them can be adjusted in height so that they can be used by tall or short players, and by players whether they are sitting down or standing up.
The most popular type of music stand is the metal one that can be folded up so that it is easy to carry about. Some music stands are made of wood. These are sometimes very ornate and therefore quite expensive.
Orchestras usually give their players very heavy metal music stands. This is because the light, fold-up ones are easily knocked over. It is also very difficult to write on music on a fold-up metal stand because there is nothing to press against (in rehearsals musicians often have to write fingering, bowing and other markings in the music).
There are also very small music stands that do not have legs and are designed to be put on a table. These can be used for any kind of instrument that can be played sitting at a table.
There are also small ones that can be attached to the instrument itself. These are used in marching bands. Thomas Jefferson, former president of the United States, invented a revolving music stand which he never patented because he wanted people to be able to use his invention for free.
There are also digital music stands. When the violinist Tasmin Little played the Ligeti Violin Concerto at a Prom in 2003 she used a special, computerized music stand that had been made for her. There were no gaps in the music where she could have turned the pages of an ordinary music score. Instead, the music was on a computer screen, and she moved to the next page by pressing a pedal with her foot. There was also another pedal for turning back a page which was important to have when practising and for rehearsal.