Adult educationCollege or University. The practice is also often referred to as 'Training and Development'. It has also been referred to as andragogy (to distinguish it from pedagogy).
Educating adults differs from educating children in several ways. One of the most important differences is that adults have accumulated knowledge and experience which can either add value to a learning experience or hinder it.
Another important difference is that adults frequently must apply their knowledge in some practical fashion in order to learn effectively; there must be a goal and a reasonable expectation that the new knowledge will help them further that goal. One example, common in the 1990s, was the proliferation of computer training courses in which adults (not children or adolescents), most of whom were office workers, could enroll. These courses would teach basic use of the operating system or specific application software. Because the abstractions governing the user's interactions with a PC were so new, many people who had been working white-collar jobs for ten years or more eventually took such training courses, either at their own whim (to gain computer skills and thus earn higher pay) or at the behest of their managers.
In the United States, a more general example is that of the high-school dropout who returns to school to complete general education requirements. Most upwardly-mobile positions require at the very least a high school diploma or equivalent. A working adult is unlikely to have the freedom to simply quit their job and go "back to school" on a full-time basis. Community colleges and correspondence schools usually offer evening or weekend classes for this reason. In the USA, the equivalent of the high school diploma earned by an adult through these programs is to pass the General Education Development (GED) test.