Vritti is the `mother of theatre` i.e. vrittayo natyamatarah, according to the Natyashastra, chapter 13. In Sanskrit aesthetics, there are three dimensions of human activity and behaviour. Thesea are verbal, physical, and mental or emotional. When such acts or behaviour take place passionately, with absorption or involvement, they spontaneously become heightened and intense. The absorption occurs in two ways, caused by the experience of joy, suffering or pain in ordinary life, or caused by the sensitivity of the artist and the connoisseur of art. The physical, verbal, and mental and emotional acts in daily living cannot be termed part of the rasa experience unless represented through an artistic process. Surcharged with artistic absorption and by the creative process, however, they get transformed into vrittis, in theatre as well as other art forms.

The individual predominance of physical, verbal, or mental/emotional responses varies from person to person, as well as in the characteristic behaviour of people collectively, from region to region. For instance, one person may be too talkative in relation to others; likewise, verbal traits may dominate in one region, compared to others. The distinctiveness of behaviour may also be observed in different psychic and corporeal states. In a specific state of being, an individual may be more silent and peaceful, while in another he may be restless and vocal. Thus vrittis become important in delineating a character, a people, or a state of being.

Vrittis are fourfold. The names can be mentioned as bharati or spoken, sattvati or internal i.e. `essence`, kaisiki or soft and graceful, and arabhati or bold and energetic. They correspond to three intrinsic channels of abhinaya or acting, namely vacika or verbal, sattvika i.e. mental and emotional, and angika i.e. physical, which covers kaisiki as well as arabhati. As corporeal actions and behaviour are visible, they are more concrete, their tenderness or vigorousness may be clearly experienced. Therefore they have been differentiated into two, kaisiki and arabhati. The former is associated with feminine behaviour, for tenderness is natural and predominant in women, whereas forceful behaviour is natural in the expressions of men. This does not mean that males lack graceful or delicate aspects and that energy is always missing in women.

These are the very general modes of human action and a play may abound in all of them or any of them according to the demands of the rasa delineated. In theatre, the vrittis are artistically improvised, the creative representation of actions or behaviour. If a play is said to have a certain vritti or vrittis, these must be highlighted in acting. Thus vrittis occupy an important place in theatre. The literary notion of style also emerges from the theatrical notion of vritti.

There are two broad categories of performance. These are sukumara or tender and aviddha i.e. vigorous. Plays full of action like war, battle, wonder, and magic, with few female characters, and featuring sattvati and arabhati vrittis, constitute the aviddha. The dima, samavakara, vyayoga, and ihamriga dramatic forms belong to this category, whereas nataka, prakarana, bhana, vithi, utsrishtikatnka, and natika belong to sukumara performance. Aviddha specially suits plays in which demons and other terrible characters occur in plenty, whereas sukumara is appropriate for drama where humans comprise the majority.

The same chapter of the Natyashastra also mentions pravritti, or specific human behaviour varying from region to region. It divides India into four broad zones accordingly, to facilitate the understanding of them, so that vrittis may find proper expression through the required portrayal in the text as well as performance. The four pravrittis are dakshinatya i.e. southern, avantika i.e. western, audramagadhi or gaudi from Magadha or Gauda i.e. eastern, and pancalamadhyama i.e. `Panchala and midland`, or north-western and northern. In each, behaviour varies due to predominance of different vrittis, requiring careful study by the playwright and actor so that description and performance achieve the accurate representation. The chapter continues by discussing the two ways of entry and exit according to pravritti i.e. dakshinatya and avantika in one group, the others in the second.