'dod pa'i khams - Desire Realm

The first of the khams gsum is 'dod pa'i khams - desire realm. 'dod pa is desire and khams is realm. The 'i between is a genitive particle that binds from right to left.

This is the biggest realm: dmyal ba, yi dvags, dud 'gro, mi, lha ma yin and parts of lha reside in this realm.

The main reason beings experience 'dod pa'i khams is that their main interest is in 'dod pa. Hence this is how they experience the world, full of desire, lack of desire, painful desire and so on.