Your breath is an amazing, unique meditation opportunity, which is why many of the techniques you'll learn here, incorporate it some way or another. What do I mean by "opportunity"?

Think about it for a moment - breathing is both a sub-conscious process (i.e., your body keeps breathing automatically whether you think about breathing or not), and a conscious process (i.e., you can take it out of "automatic" mode, and consciously control it - breathe fast, slow, deeply, shallow, hold your breath, etc.). 

Thus, breathing is a bridge between the sub-conscious and conscious minds, and you can't say that about most other bodily functions or activities.

Most of our body functions are either under sub conscious control, or conscious control. For example, a normal person can't consciously will themselves to digest their food or control their heartbeat. The subconscious does that all for us automatically. However, such things can be controlled by someone who has mastered consciously accessing the sub-conscious mind. 

On the conscious side, we do all sorts of things consciously, or so it seems. Take walking somewhere, typing or writing, thinking about what to say or do, can be conscious activities, or modified by, the subconscious. You can even program your subconscious to do, react, or take over many things you do. 

For just a little example, imagine having your computer do a spelling check on a letter or document, rather than having to look everything up manually in a dictionary. Well, you can do the same thing with most anything that involves your mind. But first you must be able to access it, and program it.

Practicing breathing meditations is one of the ways that can be used to bridge the entire gap between our conscious and subconscious minds. And it doesn't stop there. 

Many people have the problem of their conscious desires and goals being in conflict with the ones that are programmed into the subconscious mind. That is a formula for failure. For success in all areas of life, physical, emotional and spiritual, get your "minds" re-integrated so they work as one towards your goals and beliefs, rather than pulling in different directions against each other.

Breathing techniques give us a variety of ways to achieve this. As I said earlier, in many of the meditation techniques you'll find, the breath is a common denominator. And they offer many ways to use it and approach it. For instance, some breathing techniques use the fact that you can control it. Some use the fact that you can meditate on it. Some take the approach of just leaving your breath to the sub conscious mind - you leave it alone and simply watch your body breathe. Some have you concentrate on it. And some have you integrate it with other mental or physical functions.

The breath is also our link etheric, philosophical or spiritual areas. We are given life, and given breath. For those who believe in some kind of "plan", flow or God involved in the universe, you could say that it breathes each breath into us. When we cease breathing, our body ceases to live.