The dancer begins with samapada position which is the basic position with the feet facing front. The dancer's body is neither relaxed nor rigid. Thereafter the foot is turned sideways which is known as the kalai tiruppudal in Tamil. Then is the ardhamandali position in which the feet are sideways and the knees are also bending sideways. The line joining the two shoulders is considered as base of one triangle and the waist as the imaginary apex of an inverted triangle. A second triangle is conceived with the thighs as the two sides and the line joining the two knees as the base of this triangle. The space covered by the two calves and the line joining the two knees forms the third triangle.
The head forms the first unit and its lateral movements are common. The torso is seen as a whole unit. The lower limbs are seen either as straight lines or two sides of an imaginary triangle in space. The upper limbs follow the lower limbs or weave a circular pattern which is covered by the lower limbs. It is the latter aspect with the use of torso as a single unit which gives Bharatnatyam its uniqueness.
As far as foot is concerned in the first position, the entire foot touches the bound and weight is equally distributed. This is known as tattu. In the same position the second type of foot contact occurs and third type of foot contact result when the heel touches the ground and the toe is raised. Then follows the permutation and combination of these positions by the use of one foot or both the feet. The unit which emerges as a coordinated pattern of the feet, knees, torso, arms and hands is known as the adavu. These adavus can be set in a composition and can be executed in the ardhamandali position. Symmetrical pattern is achieved by executing a movement first by the right foot and then by the left foot. The first adavu is known as the tattu adavu suggesting flat foot contacts in the basic ardhamandali position.
The dancer begins her practice by stamping in single units. The dancer can execute other patterns by stamping the right foot twice and then the left foot twice. The next is a stamping sequence of right, right, left and left, left, right. These are executed in relation to different categories of talas to which these adavus are choreographed in the repertoire. The second variety of the adavu is known as nattu adavu where the foot is placed in such a way that the heel is down and the toes are up. There are many varieties of this adavu. The basic movement is that of a straight extension of one leg while keeping the other bent with the foot sideways. Leg extension is practiced by first extending one leg either to the right or to the left. The hands and arms follow the movement of the legs. As in the case of ail adavus they are practiced usually in three tempos and also with the dancer's feet for the first time covering space.
The third group has a combination of the flat feet with a slight jump on the toes. This introduces toe-heel movement. Other varieties include jumping on both toes in the ardhamandali position followed by the right foot and then the left foot stamping the ground; jumping on the toes followed by stamping of both the heels on the ground. Most of the varieties of this adavu are executed in the ardhamandali position without leg extensions. There are a number of movements where there is also a leg extension, especially a back leg extension with opposite twists of the torso. In this particular movement diagonals of arms are also emphasized.
The fourth variety is one of the distinctive features where both the toes hit the ground simultaneously followed by stamping of the heels. A sub-division of this group is the sliding or the slipping sideways of both the feet in an erect position. The dancer does glides in an erect posture sideways and then uses the heel-toe movement rather than the toe-heel movement. The final sequences are done in the third tempo which is built on this adavu.
The fifth group is where the dancer learns a variety of permutations and combinations. The first sub-division is stamping of the right foot and then the left foot, followed by a jump on the heels, on the third beat, and stamping of only the right foot on the fourth beat. This is repeated a number of times. The building of complex rhythmical structures gives a distinct style and flavour to Bharatnatyam. The sixth group has two varieties where the dancer tries to build up movement by the use of only one foot or leg in groups of three beats.
The next group known is another example of the number of permutations and combinations which can be woven around a basic movement executed to three beats. Certain varieties of this adavu provide the climax to dance sequences. The di di tai group is the use of extended leg and its contraction. In another variety, the arms weave circular patterns. The right hand which is first extended in front gradually moves back to the shoulder level on its own side. While the left hand goes back and by turning the waist, it is brought over the head and into a front-down position ending in the hasta known as the alapadma.
The eighth group known as the poi adavu means the soft silent dance patterns accompanied with graceful hops and jumps. Its distinctive feature is the lifting of the feet very silently to a new position and coming back to its original position and then the left leg being extended as in the second variety. Some jumps of Bharatnatyam belong to this group. The final and the ninth provide variation through arms and stamping in the ardhamandali position in the beginning.
The division of adavus differs from family to family in the Bharatnatyam sampradaya. The system of the adavu as a basic unit is followed rigorously, though its categories may vary. A number of these adavus can be put together to form sustained dance sequences. These patterns are known as the tirmanams. The word tirmanam is literally used for the rhythmic syllables spoken by the dance conductor as he plays on the cymbals. The tirmanam is recited vocally. The weaker beats are counted only by the fingers or waving of the hand. In the Nritta portion, the dancer first performs these patterns only to the beat of the drum and then, as she proceeds, executes them to the sung melodic line.