Alcoholism is an illness marked by consumption of alcoholic beverages at a level that interferes with physical or mental health, and social, family, or occupational responsibilities. Alcoholism is divided into 2 categories: dependence and abuse. People with alcohol dependence, the most severe alcohol disorder, usually experience tolerance and withdrawal. Tolerance is a need for markedly increased amounts of alcohol to achieve intoxication or the desired effect. Withdrawal occurs when alcohol is discontinued or intake is decreased. Alcohol dependents spend a great deal of time both drinking alcohol, and obtaining it. Alcohol abusers are "problem drinkers", that is, they may have legal problems, such as drinking and driving, or binge drinking (drinking 6 or more drinks on one occasion). People who are dependent on or abuse alcohol return to its use despite evidence of physical or psychological problems. Those with dependence have more severe problems and a greater compulsion to drink.