Deodorants help to reduce the smell caused by sweat and perspiration in the armpits. They come in various forms like roll on deodorants, stick deodorants, spray deodorants (which come in aerosol cans) and gel deodorants. Antiperspirant deodorants, in addition to covering up body odour, also prevent sweating and perspiration by blocking the sweat glands.
Deodorants are only to be applied in the armpits and should not be used on any other part of the body. They come in a variety of fragrances and if you know what you want, you'll find a scent just for you. Most products come with directions for how to use them but if the product is not branded or doesn't have any label or packaging, you can check online or ask friends for directions for use.
Consumer goods products made by manufacturers will typically come with instructions for use; if you don't find this enclosed, exercise caution before using or consuming any product you're unfamiliar with.