Finding jobs continues to be difficult for young people graduating from college. The job market has been slow to improve. Those people who do find jobs have to be clever to get into a company for an interview. Many are happy to take non-paying internships in order to get work experience. After the internship, an intern hopes to be hired or at least be recommended for another job.
The intern's presence in the office can be helpful. In a good internship, an intern is treated with respect, does a wide variety of tasks, and learns job skills. In a bad internship, an intern is treated rudely, asked to do ordinary tasks, and receives little compensation. After the internship is over, the intern may or may not be in a better position to find a paying job.