Helicobacter pylori is a gram negative bacterium, it colonizes the upper digestive system in about half of the world's population. It seems to be the biggest risk factor in the development of severely gastric complications and ultimately of malignant gastric diseases. It adheres to the gastric mucosa with polar flagella and neutralizes gastric acid by producing urease enzymes. The main virulence factors of H. pylori are the Cag A and Vac A genes. In diagnostics, we distinguish between invasive and non-invasive methods. From non-invasive methods, urea breath test, stool antigen test and serological tests for IgG specific antibodies are used, while the main invasive method of choice in the diagnosis of bacteria is upper gastrointestinal tract endoscopy with biopsies. Standard eradication therapy also known as "triple therapy" consists of a combination of IPP, amoxicillin and metronidazole. Although the target organ of H. pylori is the stomach, there are numerous extragastric complications. In neurological diseases, the possibility of bacterial inpact on the severity of Parkinson's and Alzimer's disease has been observed, while in cardiac diseases H.pylori is associated with the development of coronary artery disease and is also suggested as the independent risk factor for the development of essential hypertension. In hepatobiliary diseases, it is associated with non-alcoholic fatty liver disease, liver fibrosis, as well as autoimmune liver diseases. The link between rosacea and H. pylori is already known, as is idiopathic thrombocytopenic purpura and iron deficiency anemia. On the other hand, the protective effects of infection have been observed in inflammatory bowel diseases. Many other mostly adverse effects as well as some protective effects have been described, but they are not listed in this article. As H. pylori is a strong risk factor for the development of esophageal, stomach and duodenal malignancies, its eradication has proved to be an important factor in their prevention. New biomarkers such as miRNAs, or well known serum pepsinogens are used in the bacterial identification in order to detect malignant complications as early as possible. However, the endoscopic method of early malignant detection is the gold standard and significant advances in the development of new endoscopic methods are being made.