1. We need dictionaries as helpers for the translation of words and phrases from the foreign languages.
2. There are many types of special dictionaries - scientifical, medical, technical dictionaries as well as those for engineers, sailors or simply the tourists.
3. Students of foreign languages may need differend kinds of dictionaries - it depends on what speciality they study foreign languages for. But every student of foreign languages for sure needs common dictionary, which includes translation of words from foreign language to the native one and vice versa.