On-the-job training (sometimes abbreviated OTJ or OJT, and sometimes called direct instruction) is one of the earliest forms of training — observational learning is probably the earliest. It is one-on-one training located at the job site, where someone who knows how to do a task shows another how to perform it.
In antiquity, the work performed by most people did not rely on abstract thinking or academic education. Parents or community members, who knew the skills necessary for survival, passed their knowledge on to the children through direct instruction. This method is still widely used today. It is a frequently used because it requires only a person who knows how to do the task and the tools the person uses to do the task. It may not be the most effective or the most efficient method at times, but it is normally the easiest to arrange and manage. Because the training takes place on the job, it can be highly realistic and no transfer of learning is required. It is often inexpensive because no special equipment is needed other than what is normally used on the job. One drawback is that OJT takes the trainer and materials out of production for the duration of the training time. In addition, due to safety or other production factors, it is prohibitive in some environment. Even many researchers show the importance of the On the Job Training. For instance, in a research conducted by Arun Paul confirms the significance of providing social skills training to professional social workers.
A large majority of employee learning is accomplished through on-the-job training. Well designed OJT training programs are well planned and resourced, staff managers with competent coaching ability, and define the criterion for performance standards.
Source: Wikipedia