Deodorants work by stopping your sweat glands from working. When your sweat glands don't work, you can not secrete sweat. This also prevents the bacteria from growing in their own little filthy kiddie pool . They won't be able to produce smell and voila! You won't reek anymore.

Aerosols

These are a bad option for the environment as they release CFCs and destroy the ozone layer.

Roll-Ons

These are better options for the environment but may be harsh on skin.

Natural Deodorants

These include minerals and even fruit extracts like lemon juice. These have both antiperspirant effect and keep your pits looking good without harsh chemical changes.