What is structural unemployment?
Structural unemployment is when a worker's skills are not those necessary for the job.
Say there is a worker who was trained in computer software (programming, installing, etc.). He or she goes and looks for a job. But there are no jobs involving computer software. The only job available is a job as a chef. The worker's skills in software do not meet the requirements for the chef job. Therefore, he cannot find a job and is unemployed.
But this is a special type of unemployment. Because his skills don't meet that of the job offered, he is structurally unemployed.