Dictionaries come in different levels of proficiency; such as advanced, intermediate and beginner, which learners can choose accordingly to the level best suited to them. There are many different types of dictionaries available; such as thesaurus or bilingual dictionaries, which cater to the specific needs of a learner of a foreign language. In recent years, there is also specialised dictionaries for foreign language learners that employ natural language processing tools to assist in the compilations of dictionary entries by generating feedback on the vocabulary that learners use and automatically providing inflectional and/or derivational forms for referencing items in the explanations.