These will be the people who directly support your music financially but buying your music. They should generally have a good disposable income (Be willing to spend money on leisure products i.e. buy your music) and be able to access your music easily, whether via the type of shop they would go to, or online.
School children are often in this category, as they tend to get pocket money which they can spend on whatever they want. Younger children also often ask their parents to buy them the latest music, so if your music if child friendly (Is catchy and doesn’t have any swearing / provocative subjects) this could be a big market for you. If however your music does have swearing, older secondary school children are still a good bet for you as they’re old enough to hear obscenities yet still have enough disposable income to buy your music.