Pratimoksha (individual liberation) vows are based on taming one’s physical behaviour and not causing harming to others. Without taming our behaviour, nor avoiding all types of negative actions, we cannot undertake any spiritual training, nor improve on the spiritual path. We strive to avoid all causes which give rise to conflicting emotions, roots of Samsara binding habits and create a clean and stable basis to bring peace, joy and happiness to oneself and others.
Pratimoksha vows are thus called the foundation of Buddhism. By following those vows, we are seeking self-liberation and will lead to the state of svravakas. These vows must be practiced with a strong following of Bodhicitta, wishing all beings to achieve happiness and the causes of happiness, as well as becoming free from Samsara, as we are also followers of the Great vehicle of the Mahayana. .
We can differentiate eight precepts categories.
One, who is sometimes discounted as a precept is only taken for a short period of twenty-four hour. In it the upavasika practitioner observes eight vows.
The upasaka (male lay householder) and upasika (female lay householder) observe five precepts. These first three are the precept categories for lay householders.
The sramanera (male novice) and sramanerika (female novice) observe ten, thirteen, or thirty-six vows. The siksamana (female novice in training) observe twelve vows in addition to the precepts of a sramanerika. The bikshu (fully ordained monk) observes 253 vows, and the bikshuni (fully ordained nun) observes 364 vows. These five are the precept categories for those who are celibate and have renounced worldly life. In Tibetan monastic practice, the last seven Pratimoksha categories are taken for the duration of one’s life.
For a fully ordained monk, the total precepts to be rejected are two hundred and fifty-three. These are classified into six categories:
1) Category of root downfalls
2) Category of remainders
3) Category of rejected downfalls
4) Category of solitary downfalls
5) Category of individual confessions
6) Category of faults
Precepts to be followed are:
1) The three foundations for all training
Sojong (uposatha) confessional ceremony
Yarney (varsika) rainy season retreat
Gagye (pravarna) lifting restrictions ceremony
1) The seventeen basics
2) The twelve ascetic practices
3) The four dharmas of sramana
There are three ways in which the lineage of Pratimoksha vows came to Tibet from the Sarvastivada School. There are known as the Lower lineage of Vinaya or sMad-dul brought in a uninterrupted pure line from Lord Buddha to Tibet by Khenpo Santarakshita and is the base for ordination for all Nyingma monks as well as many Gelugpas, the middle lineage of Vinaya or Bar-dhul, who is the tradition of Nagarjuna and forms the base of ordination for Sakya and Kagyudpa monks and the upper lineage or sTod-dul from the Indian Pandita Dharmapala. The latter lineage was the basis of ordination for Sakya Pandita 1181-1251, but became extinct in Tibet and it is not uncommon to hear the second lineage referred to as the upper lineage. 
The reason why we are observing so many vows is a way to protect ourselves against the weakness of our minds, easily prey to emotions such as anger, greed and lust. At first the vows are like physical disciplines, but as our minds grow stronger in healthier habits, we can turn our attention to developing the other types of vows, Bodhicitta and tantric vows.
 Upper and lower refer to parts of Tibet where the vows were preserved and perpetuated after the massive destruction and near eradication of monks under the realm of King Langdarma hostile to Buddhism