Hindi marks grammatical relationships with postpositions (परसर्ग) that follow the noun, where English would place a preposition before it. This reference lists the major postpositions with their meaning, the case they govern, and a worked example.
How it works
Hindi has a two-way case system in the singular: the direct case (used when there is no postposition) and the oblique case (used whenever a postposition follows). The single most important rule is:
Any postposition forces the preceding noun or pronoun into the oblique case.
So लड़का (boy, direct) becomes लड़के before any postposition, and the pronoun मैं (I) becomes the oblique stem मुझ before को, giving मुझको. Possessive का/के/की additionally agrees in gender and number with the thing possessed, not the possessor.
Tips and examples
Compound postpositions such as के लिए (for), के साथ (with), and के बारे में (about) are built on the genitive के, so the noun before them is still oblique: तुम्हारे लिए (for you), not तुम के लिए. Use the search box to jump to a postposition by its English meaning, its Devanagari spelling, or its romanisation, then copy the example phrase as a model for your own sentence.