Helicobacter pylori is a gastric pathogen infecting >half of the world's population, leading to gastric mucosa chronic inflammation and can evolve into gastric cancer. In humans, H. pylori bacteria may colonize alternative sites of the digestive system and associate with inflammation and different extra gastric tumors. This review focuses on H. pylori epidemiology, transmission routes, and its role in gastric extra-gastric and cancers. Also, different H. pylori virulence factors and their role in carcinogenesis were discussed.