What does one achieve by Yoga? In Sanskrit, "Yoga" signifies 'connecting the soul to the Supersoul' (God). Yoga is a process in which the person clears the negative mental impressions, gets the mind and senses under control and creates a connection or link with God. In Patanjali Yoga Sutra, an authentic textbook of Yoga, the definition of Yoga is given as follows: 

Yogash chitt vritti nirodha 

A simple translation of this verse reads, "the complete stopping of mundane desires arising in the mind is known as Yoga". The mind is an ocean of material desires, not only from the present life, but also from previous lives. According to Vedic philosophy, the mind along with subtle body, senses and soul, transmigrates from one body to another. Mundane desires that arise in the mind remain there, and unless one cleanses the mind of these, it is not possible to realize the consciousness or the soul. And without the realization of the soul or consciousness, it is not possible to connect it to God. Therefore to connect to God, which is also termed as moksha or Liberation, it is necessary to stop or remove such desires from the mind. 

This process of removing of mundane desires from the mind, realizing what is "consciousness" or "the soul" and then connecting it with God, is known as Yoga. Yoga is a discipline, a process that one has to practice. Depending on which method a person follows to curb such desires, Yoga is classified into many types as follows: 

1) Gyana yoga - Attaining realization through knowledge. 

2) Karmayoga - Attaining realization through action. 

3) Bhaktiyoga - Attaining realization through devotion. 

4) Mantra yoga - Attaining realization through mantra (chanting special words or 
    prayers of God). 

5) Rajyoga - Attaining realization through meditation. 

6) Hathayoga - Attaining realization through practice (physical, mental processes) and
    meditation. 

Astanga (eight parts) of Yoga: 

The Patanjali Yoga Sutra describe eight parts of Yoga, known as Astanga Yoga. Asta means 'eight' and anga means 'parts'. The following are the eight parts of Yoga according to Patanjali. 

1. Yama 
2. Niyama 
3. Asana 
4. Pranayama 
5. Pratyahara 
6. Dharana 
7. Dhyana 
8. Samadhi 

The ultimate goal of Yoga is to attain the stage of samadhi, which is the eighth and last part of Yoga. In this state, a man is away from all types of materialistic associations and is linked to God. To achieve samadhi, one has to start from Yama and practice all the eight parts sequentially. 

1. Rules or Yama
Yama is a set of rules that a person desiring to practice Yoga should know about, and follow. It is the foundation and in order to achieve the highest state of samadhi, one must follow the rules. The following are the five basic rules, which should be strictly followed to get the best benefits. It is interesting to note that many people in the modern age practice Yoga, especially physical exercises (asanas), without strictly following the yama and niyama (rules and regulations). Such people may not achieve the ultimate goal of Yoga, as they are not following the proper process to reach samadhi. 

The following five are known as yama. 

a) Ahimsa: Nonviolence
b) Satya: Truthfulness, speaking the truth.
c) Asteya: Abstinence from theft
d) Brahm-charya: Celibacy
e) Aprigraha: Not accumulating more than what is required.

2. Regulations or Niyama:

Niyama is a set of five more rules and regulations which play an important role to create a strong foundation for a person wishing to practice Yoga and attain moksha or liberation. The only difference between yama and niyama is that the yama are rules relating to external factors, whereas the niyama are rules relating the individual's internal self. The following are the five niyama: 

a) Shaucha: Purification, cleanliness.
b) Santosha: Satisfaction.
c) Tapa: Practice of controlling the mind and the senses.
d) Swadhyaya: Studying spiritual books.
e) Ishwar Pranidhana: Surrendering everything to God.

The first two steps of Yoga, according to Patanjali Yoga Sutra, relate purely to the psychological plane - they are about disciplining the mind and preparing an individual for the more challenging rigors of Asana (postures) and Pranayama (breathing exercises), integrated with the subsequent steps and culminating in Samadhi.

3. Physical Postures or asana: 

Asana is the next part of eightfold Yoga. The asanas are postures that mainly benefit physical health. They help in keeping the body healthy which ultimately makes the mind healthy because the mind and the body are closely related. In order to get the best results or benefits from the asanas, it is important to practice yama and niyama. There are many people practicing asanas without following yama and niyama. Some of them do not even know that Yoga has eight parts. They think Yoga means asanas. 

4. Breathing Exercises or Pranayama 

This is the fourth part of Yoga. After a person attains stability in the asanas and the various body functions normalize, pranayama is performed. It is very important to understand the step-by-step progress, which means the person, should start with yama, niyama, asanas and then practice breathing exercises. Many people practice pranayama without fully following the previous steps. Although this may give temporary benefits, it would never lead a person to achieve the ultimate goal of Yoga. So it is important to practice every activity step-by-step. 

Pranayama is made up of two words - prana meaning 'life air' (prana vata) or 'breath', and ayama, meaning 'to control'. So pranayama is a procedure wherein an individual practices controlled breathing. Pranayama is not merely a respiratory exercise - it purifies the brain and rejuvenates the nervous system. Pranayama is thus a very important exercise both for maintaining health and curing diseases. 

5. Self-regulation or Pratyahara

It is a process of self-regulation. In this process, the person controls the sense organs and keeps them away from their subjects. It is a stage where the Yogi starts to cut off from the external world by controlling the mind. Whenever one wants to control the mind, three types of changing sequences are produced in the mind, which are as follows:

1. Waves of various emotions produced by the external world. 

2. Waves of experiences from the past. 

3. Waves of happenings of the future.

Of these, the second and the third are completely psychic and the goal of Pratyahara is to disconnect the mind from the first type of waves. 

Dharana, Dhyana, and Samadhi are collectively called sanyam. These three steps constitute the spiritual aspect of Yoga. Samadhi is a state of complete mental rest in which the person is away from all the materialistic feelings and is close to God. 

6. Concentration of the Mind or Dharana: 

Dharana means concentration of the mind. To concentrate the mind at a point in the body or outside the body is called Dharana. Inside the body, there are two places of concentration: 

Nasa-agra - the tip of the nose and 
Bhrumadhya - between both the eyebrows 

Dharana is the first step towards spiritual realization. It is a type of psychological exercise. One should try to obtain more and more concentration and gradually extend the period of total concentration. 

7. Meditation or Dhyana: 

Dhyana means meditation. Concentrating the mind on a subject continuously is Dhyana. This stage precedes Samadhi. In this, the mind gets stable over a subject and no other thoughts come during concentration. This is of two types:

1. Saguna: In this type of meditation, the person meditates on an object, to achieve dhyana.

2. Nirguna: In this type, meditation is practiced without any specific object in mind. In fact, this Nirguna state of meditation actually precedes total Samadhi. 

8. Connecting to God or Samadhi:

This is the last stage when all external and internal matters slip into oblivion. It is a stage envisaging the destruction of all mental activity. According to Ayurveda, sense organs confer their subjects to the mind, which turns to the soul. In the stage of Samadhi, the relation between the soul and the mind is destroyed and the soul connects with God. Thus the highest stage of concentration is reached, which is the ultimate goal of Yoga. In this stage, self-awareness disappears. During Dharana, there is very little mental distraction. During Dhyana, the frequency of self-awareness decreases, and in the final stage of Samadhi, the soul is weaned away from all types of distraction and self-awareness. The Atma (soul) combines or connects with the Paramatma (Supersoul or God). It is at this stage that man acquires psychic abilities and attains supreme knowledge. The Yogi or the person develops various supernatural powers known as siddhi. Thus the eight steps of Yoga culminate in the state of samadhi. Although this is a very detailed and slow process and requires a lot of training, this brief description will help us understand what Yoga is all about

Source: Medi-Serve India