A professional criminal is a person who pursues criminal activity as their primary day-to-day occupation and source of income, developing specialised skills, techniques, and a certain level of status and recognition within the criminal underworld. Unlike amateur or occasional offenders, professional criminals often plan their crimes carefully, work in organised groups or networks, and may have a long-term commitment to a life of crime. They often develop a code of conduct and may view their criminal activities as a career, acquiring expertise in specific types of crime such as theft, fraud, drug trafficking, or gambling.