Anapana Sati (Mindfulness of breathing)

Anapanasati is an ancient practice. Every meditation technique needs an anchor, and the breath is one of the most obvious one to use. We know from early Buddhist texts that it was one of the main practices that the Buddha taught his disciples, but there’s no doubt that he didn’t invent it. Rather, most likely, he learnt it from his early yoga teachers, Alara Kalama and Udaka Ramaputta who taught it as a concentration (Samatha) practice used to reach altered states of consciouness (known in Buddhism as Jhanas and in yoga as Samadhi). Indeed, the breath is one of the best object of meditation to reach these states.
What the Buddha may have discovered, though, is that Anapanasati can also be used as a wisdom (vipasana) practice.
The Anapanasati sutta details sixteen steps, all of them based on the awareness of the in and out breath, which take the practionners through the four foundations of mindfulness (body, feelings (vedana), mind and dharma). These sixteen steps proceed through increasingly subtle subjective experiences towards awareness of the impermanent nature of all experiences. The Anapanasati sutta, by emphasing various phenomenas related to the process of breathing, demonstrates how breath centered practices can also be used to develop insight. Since this discourse was delivered to experienced practionners who had been on retreat for three months, it is reasonable to assume that most of them would have been familiar with the use of breathwork to access Jhanas / Samadhi states.
Because it can be used to develop both calm (Samatha) and wisdom (Vipasana), anapanasati is a meditation practice that will benefit students of all levels and it should therfore be introduced as early as possible.