This cluster of papers explores the complex landscape of functional bowel disorders, with a focus on conditions such as irritable bowel syndrome, constipation, and gastroparesis. It delves into the role of microbiota, enteric nervous system, and intestinal permeability in these disorders, as well as the potential therapeutic impact of probiotics and serotonin signaling. Additionally, the cluster addresses the prevalence, epidemiology, and global burden of functional gastrointestinal disorders.