Contrastive analysis and error analysis are approaches to understanding second language acquisition. Contrastive analysis focuses on differences between a learner's first language and the target language, believing errors stem from transferring habits from the first language. Error analysis takes a more scientific view, seeing language acquisition as a cognitive process and errors as natural reflections of developing linguistic rules. Interlanguage theory posits learners develop their own internal language system, not an imperfect copy of the target language. Various taxonomies classify types of errors learners make.