Halitosis is a common and devastating condition, which may affect up to 1/3 of the population. It can be classified either as genuine halitosis, pseudohalitosis, or halitophobia. Genuine halitosis is more common and usually related to an organic pathology such as periodontitis. Malodour molecules such as sulfur compounds that arise from bacterial interactions generate the basis of oral malodour. Pathologies of the tongue, poor oral hygiene, deep caries, cryptic tonsillary hypertrophia, and postnasal drainage are also associated with halitosis. Gastro-esophageal pathologies and systemic problems are accepted as extra-oral sources of halitosis. There are various methods for the diagnosis of halitosis including objective and subjective methods. General oral hygiene recommendations and specific interventions for the related etiological factors have to be addressed in order to achieve satisfactory results after the treatment. Clinicians have to be aware of these aspects regarding this unfavorable condition to achieve the best results.