What are three realms? What are six ways of sentient existence?

The three realms—the Triloka—are that of desire, that of form, and

that of formlessness.

There in the realm of desire, forms of desire for sex and food

predominate, and all living beings dwell everywhere from the six

heavens of desire, to the four inhabited continents of each universe

where we are, and down to the hells; there in the realm of form, all

living beings with outward appearance dwell in the four dhyana heavens

or eighteen Brahma heavens; and there in the realm of formlessness,

all living beings with mind and cognition anchoring in the ability to

overcome all disturbing thoughts dwell in the four immaterial heavens,

namely, the states of boundless space, of boundless knowledge, of

nonexistence, and of neither thinking nor not thinking. The three

realms, conclusively, are where ordinary human beings journey between

rebirths and redeaths. Practitioners emulating the Buddha need to

focus on liberating themselves from transmigration and strive hard in

pure progress.

The six ways of sentient existence are the three virtuous paths and

three evil paths of transmigration combined. The three virtuous paths

pertain to the heavens, human realm, and azura state, and the three

evil paths to the hells, hungry ghosts, and animals. The six ways of

sentient existence denote the process in which all living beings therein

generate a certain cause to duly beget a certain result and hence

proceed from cause to effect. The six ways of sentient existence are

also known as six destinies.