What is breath?

There is a lot of talk on breath, now what is breath? What's the meaning? Is it form? What of it? Is it an action? Is it a perception? A feeling? How should it be taken, if to be taken, so that it would be used right, focused on it right? **Addition: It should be seen to be encouraged to give answers after own investigations on field, having investigated breath, in and of itself.** *(Note: this is not given for exchange, stacks, trade or entertainment but as a means for liberation from this wheel.)*