Biomarkers in inflammatory bowel disease are an essential tool in clinical practice. They allow a non-invasive evaluation of patients and thus guide decision-making at different stages of the disease, including diagnostic suspicion, severity assessment, relapse prediction, and treatment response. Although biomarkers in blood such as erythrocyte sedimentation rate and C-reactive protein, are the most commonly used biomarkers, because their low cost and accessibility, they lack specificity. Currently, fecal biomarkers offer greater reliability, applicability, and specificity. Fecal calprotectin is the most commonly used marker. This review discusses the advantages and disadvantages of biomarkers in inflammatory bowel disease, as well as their clinical applications and new biomarkers currently under research.