Substance use disorders are complex conditions characterized by compulsive drug-seeking behavior despite negative consequences. These disorders affect the brain's reward system, leading to tolerance, withdrawal, and cravings. Understanding the neurobiology, risk factors, and diagnostic criteria is crucial for effective treatment. Various substances, from alcohol to opioids, have unique effects and associated risks. Treatment approaches include detoxification, pharmacotherapy, cognitive-behavioral therapy, and support groups. Social and cultural factors play a significant role in addiction, while ongoing research explores new interventions and addresses controversies in the field.