Mistakes are either errors or slips. There are two main reasons why learners make errors:
* L1 interference and the stage of learner's development.
* Mistakes result in problems of accuracy, appropriate.
* Mistakes can of course be oral or written.
* Inaccuracy: grammatical
* Inaccuracy: pronunciation
* Inappropiate style / register
* Inaccuracy: lexical
* Inaccuracy: spelling
* Inaccuracy: punctuation