Bad Breath (halositosis) is a term used to describe unpleasant odour coming from oral cavity.
80-85% sources of bad breath comes from inside the oral cavity. Any food that's left inside the oral cavity will eventually be dissolved by oral bacteria and turned into unpleasant smelling odour such as Methyl Mercaptan, Hydrogen Sulphide and others. Another main source of bad breath is dental plaque, a community of microorganism that can cause Gingivitis, gum inflamation that can causes Bad breath.
Other sources of bad breath such as saliva deficiency that can cause deficiency of Streptococcus Salivarius, a species of bacterium that can reduce bad breath. And Tonsillitis can also cause bad breath.
Bodily diseases can also cause bad breath. Non orally related diseases such as Sinusitis, Bronkhitis, Diabetes, Renal and Liver failure can also cause bad breath.
Bad breath is mostly caused by lack of oral hygiene. So, don't forget to bruh your teeth at least twice a day. Occasional floss and tongue clean up can also increase your dental hygiene.
Foods and drinks such as tea, and cinnamon can also reduce bad breath. Chewing gum can stimulate saliva secretion that in turn reduce bad breath.