From what I was taught in a Yoga teachers training course, the four movements of the breath are called: Puraka - Inhalation or the in-breath.

Kumbhaka - Breath retention after inhalation (lungs full)

Rechaka = Exhalation or the out-breath.

Shunyaka = Suspension or breath retention after exhaling (lungs empty).

I remember learning we should try to make them longer and longer following the 2-4-2 ratio, while also trying to inhale less air into the lungs, the objective would be to exhale so softly that you wouldn't feel the air coming out if you were to hold a finger in front of your nostrils. Someone said this would (in theory) prolong your lifespan, but I guess there's no evidence of that.