What are type a and type b personalities?

Typically, a Type A personality is a high-stress, on-the-go individual. Stock brokers, CEO's and other aggressive personalities tend to be Type A.

Type B individuals are more laid back, easy-going and not as prone to stress.

There's also what's been called a Type T person, who seems to be addicted to thrills. Those are your daredevils and athletes. But it's all fairly pop science.