Like as in English there is no declension of nouns. Prepositions are used to express declension.
We split all prepositions into two groups:
1. Prepositions which are added to words as prefixes, without spaces. There are exactly four prepositions in this group:
- ב (in, into, by, using);
- ל (toward, for);
- כ (as);
- מ (from, out of).
With these prepositions (except of מ) a definite article is never used, even if it should be by the rules above. The preposition מ can be inserted before an article.
2. Prepositions which are separate words. There are a few prepositions of this kind. You can use a dictionary to identify them.