John Holland classified personality based on Occupation/Interest into six categories.
Realistic
Investigative
Artistic
Social
Enterprising
Conventional

1. Realistic (Outdoor and Technical Interests):
Realistic individuals are likely to work with plants, animals, machines, or tools. They avoid social activities such as teaching or informing others and prefer to learn by doing in a practical, task-oriented setting.
Example: Farmer, electrician, engineer.
2. Investigative (Thinkers):
Investigative individuals are analytical, intellectual, and observant. They enjoy research-based, mathematical, or scientific activities and focus on creative problem-solving. They often work autonomously and do not seek leadership roles.
Example: Medical technologist, biologist, chemist, systems analyst.
3. Artistic (Creators):
Artistic individuals are original, intuitive, and imaginative. They enjoy creative activities such as composing or playing music, writing, drawing or painting, and acting in or directing stage productions. They seek opportunities for self-expression through artistic creation.
4. Social (Helpers):
Social individuals are humanistic, idealistic, responsible, and concerned with the welfare of others. They enjoy group activities and helping, training, healing, counselling, or developing others.
Example: Psychologist, therapist.
5. Enterprising (Persuaders):
Enterprising individuals are energetic, ambitious, adventurous, sociable, and self-confident. They enjoy activities that involve persuading others, such as sales, and often seek leadership roles. They are effective public speakers.
Example: Salesperson, business executive, manager.
6. Conventional (Organisers):
Conventional individuals are comfortable working within an established chain of command and prefer carrying out well-defined instructions rather than assuming leadership roles. They prefer organised and systematic activities.
Example: Secretary, accountant, banker.