Inflammatory bowel disease is a chronic relapsing disease of the digestive system with an unpredictable clinical course. Crohn's disease and ulcerative colitis are the two main entities of the disease. The term indeterminate colitis is used for cases which cannot be classified as Crohn's disease or ulcerative colitis due to the lack of diagnostic criteria. As the incidence and prevalence of inflammatory bowel disease has increased over the last decades, it is becoming a significant health problem. Despite numerous studies, the etiopathogenesis is still not fully understood. According to current knowledge, chronic intestinal inflammation occurs as a result of a complex interaction between the genetic predisposition of the host, an inappropriate innate and adaptive immune response, altered intestinal microbiota and environmental factors. Diagnosis of inflammatory bowel disease relies on a combination of clinical presentation, laboratory testing, endoscopy with biopsy and radiological imaging. Symptoms depend on the extent of the disease and the intensity of the inflammation. Beside intestinal symptoms such as diarrhea, blood and mucus in the stool and abdominal pain, there are numerous extraintestinal symptoms that often occur. Endoscopy with biopsy is the gold standard for distinguishing Crohn’s disease from ulcerative colitis. Furthermore, it is essential for determining the extent and activity of the disease, which has an impact on the choice of therapy. According to the guidelines, several different groups of drugs can be used in the treatment and, if necessary, surgical procedures. The development of immunomodulatory and biological therapy has led to significant advances in the treatment.