Functional gastrointestinal disorders (FGIDs) are the most common diagnoses in gastroenterology, characterized by morphological and physiological abnormalities such as motility disturbances, visceral hypersensitivity, altered mucosal and immune function, gut microbiota changes, and central nervous system processing. The Rome Foundation has played a pivotal role in developing diagnostic criteria, with Rome IV being the latest update, which includes updates to basic and clinical literature, new information on gut microenvironment, gut-brain interactions, pharmacogenomics, biopsychosocial aspects, gender, and cross-cultural understandings. Rome IV also reduces the use of imprecise terms, uses updated diagnostic algorithms, and incorporates patient illness experiences and physiological subgroups or biomarkers for more targeted treatment. The history of FGIDs dates back to ancient times, but their understanding evolved from a dualistic perspective to a biopsychosocial model. The Rome Foundation, established in the late 1980s, has been instrumental in operationalizing research and disseminating knowledge. The biopsychosocial model integrates biological, psychological, and social factors, providing a comprehensive framework for understanding and treating FGIDs. The evolution of FGID classification and diagnostic criteria is detailed, from the early working teams to the publication of Rome I, II, III, and IV. Rome IV addresses limitations of previous versions, such as the imprecise term "functional GI disorders," cumbersome diagnostic criteria, and a lack of precision in identifying physiological subgroups. The new definition of FGIDs as disorders of gut-brain interaction reflects current scientific knowledge and is nonstigmatizing. The Rome IV classification and criteria are primarily based on symptoms rather than physiological criteria, with physiological criteria allowed for anorectal disorders. The classification covers 33 adult and 20 pediatric FGIDs across various anatomic regions. The Rome committee process involved rigorous data gathering, synthesis, and peer review. Rome IV introduces new diagnoses with known etiologies, reclassifies some disorders, and changes the criteria for irritable bowel syndrome (IBS) subtypes. It also removes the term "discomfort" from IBS criteria and combines chronic nausea and vomiting disorders. The biopsychosocial model of FGIDs emphasizes the interplay between early life factors, psychosocial development, and physiological functioning, influencing clinical presentation and outcomes. This model provides a comprehensive approach to understanding and managing FGIDs.Functional gastrointestinal disorders (FGIDs) are the most common diagnoses in gastroenterology, characterized by morphological and physiological abnormalities such as motility disturbances, visceral hypersensitivity, altered mucosal and immune function, gut microbiota changes, and central nervous system processing. The Rome Foundation has played a pivotal role in developing diagnostic criteria, with Rome IV being the latest update, which includes updates to basic and clinical literature, new information on gut microenvironment, gut-brain interactions, pharmacogenomics, biopsychosocial aspects, gender, and cross-cultural understandings. Rome IV also reduces the use of imprecise terms, uses updated diagnostic algorithms, and incorporates patient illness experiences and physiological subgroups or biomarkers for more targeted treatment. The history of FGIDs dates back to ancient times, but their understanding evolved from a dualistic perspective to a biopsychosocial model. The Rome Foundation, established in the late 1980s, has been instrumental in operationalizing research and disseminating knowledge. The biopsychosocial model integrates biological, psychological, and social factors, providing a comprehensive framework for understanding and treating FGIDs. The evolution of FGID classification and diagnostic criteria is detailed, from the early working teams to the publication of Rome I, II, III, and IV. Rome IV addresses limitations of previous versions, such as the imprecise term "functional GI disorders," cumbersome diagnostic criteria, and a lack of precision in identifying physiological subgroups. The new definition of FGIDs as disorders of gut-brain interaction reflects current scientific knowledge and is nonstigmatizing. The Rome IV classification and criteria are primarily based on symptoms rather than physiological criteria, with physiological criteria allowed for anorectal disorders. The classification covers 33 adult and 20 pediatric FGIDs across various anatomic regions. The Rome committee process involved rigorous data gathering, synthesis, and peer review. Rome IV introduces new diagnoses with known etiologies, reclassifies some disorders, and changes the criteria for irritable bowel syndrome (IBS) subtypes. It also removes the term "discomfort" from IBS criteria and combines chronic nausea and vomiting disorders. The biopsychosocial model of FGIDs emphasizes the interplay between early life factors, psychosocial development, and physiological functioning, influencing clinical presentation and outcomes. This model provides a comprehensive approach to understanding and managing FGIDs.