PranaYama is the conscious direction and mastery of the flow of Prana or Vital Life Current and is also the collective name given to all breathing techniques in the practices of Yoga.
Scroll definitions on Prana and Breath for further reading.
Some are beginners practices and some are advanced practices.
Natural Breathing, Abdominal Breathing, Thoracic and Clavicular Breathing and Full Yogic Breath that uses all three of the latter techniques are Yogic beginners level Pranayama Practice.
One can be a beginner in these for a lifetime and when practiced regularly they do provide a wonderful stepping stone to more advanced breathing techniques such as Nadi Shodhana (Alternate Nostril Breathing), Kapalabathi (Breath of Fire), Ujjaji (Victorious Breath) and more.
When I teach breathing practices I separate Breath-Work from PranaYama.
This to clarify where the former is a foundation practice and the latter an advanced practice requiring extensive prep from the practitioner and also much deeper knowledge is required of the teacher. What makes a practice advanced is if the practitioner is to practice the techniques daily or regularly then further preparation is needed. If practicing the advanced techniques every now and then to explore them occasionally and for a few minutes only it is possible to engage in them safely with the help of an experienced teacher. For regular or long practice however, gradual preparation is necessary.
PranaYama begins with breathing better and gradually deepens into the subtle energy activities of gathering and moving and absorbing Prana from the surroundings and from and through ones own system of life. Each technique fosters the clearing and strengthening of particular channels of energy in the body that vitalises organs and systems, blood and nerves and goes on to purify the subtle energy body (Nadis). When the central Nadis are cleared through PranaYama there is safe passage for Kundalini awakening. PranaYama is considered a direct path to Self-Realisation in the Raja Yogic / Hatha Yogic Spiritual Traditions. This level of PranaYama is a stage of mastery of Prana and Hatha-Yogic Practice.
Ultimately, in deep states of meditation, the Yogi Master can sustain life without breath and the body is sustained on Prana and by the power of God Conciousness alone. This prolonged breathless state is considered one of the highest levels of Yogic mastery.
YM defintion :
Pranayama - the rhythm of life current - Breath movement patterns with specific energetic resonance for spiritual evolution
Further Scrolls: Prana, Breath, YM Pranayama, Breathwork,