Testing is used to measure a person's knowledge, skills, or abilities in various topics. There are several types of language tests that serve different purposes. Proficiency tests measure overall language ability, achievement tests evaluate how well learning objectives were met, diagnostic tests identify strengths and weaknesses, and placement tests determine what level is appropriate. While final achievement tests directly relate to course content, they can provide misleading results if the course or materials were poorly designed, as successful test performance does not necessarily indicate true achievement of all learning objectives.