An achievement test is a test of developed skill or knowledge. The most common type of achievement test is standardized test developed to measure skills and knowledge learned in a given grade level, usually through planned instruction, such as training or classroom instruction. Achievement tests are often contrasted with tests that measure aptitude, a more general and stable cognitive trait. A proficiency test is usually commissioned by a nation for those who are a second language learner of the language of the nation. It is often divided into several levels from the basis one to the highest grade. And it is conducted according to different abilities, generally including reading, listening and writing.