On-the-job training focuses on the acquisition of skills within the work environment generally under normal working conditions. Through on-the-job training, workers acquire both general skills that they can transfer from one job to another and specific skills that are unique to a particular job. On-the-job training, typically includes verbal and written instruction, demonstration and observation, and hands-on practice and imitation. In addition, the on-the-job training process involves one employee—usually a supervisor or an experienced employee—passing knowledge and skills on to a novice employee.

On-the-job training is the oldest form of training. Prior to the advent of off-site training classrooms, the only practical way of learning a job was working along side an experienced worker in a particular trade or profession—as evinced by the practice of apprenticeship during the Middle Ages when master craftsmen passed on skills and knowledge to novices who worked along side them.

On-the-job training is still the predominant form of job