It is also known as Golu, Kolu, or Bommai Kolu etc.
During Navratri, it is customary in Tamil Nadu to display a "Golu". This is an exhibition of various dolls and figurines in odd (usually 7, 9, or 11) numbered tiers ("padis"). There is huge difference in organizing Golu in USA (or outside India) and in Tamil Nadu. Apart from creativity, there are lots and lots of resources available in India. You can pretty much get what you want to display and help to set it up as well. I have known instances where doll making artisans go to the Golu location to complete building the intricate doll displays. Here is USA, the household organizing the Golu has to practically perform every task starting from picking up wooden Golu steps from Home Depot to finally packing up the contents in boxes and taking to the basement for storage. Of course, increasing number of people displaying Golu now a days makes it easy share the tricks to make the process efficient. Now at least you can order the dolls locally online through navarathri.com and other such websites so they can be delivered to your door, saving you the hassel of lugging all the way from India in your suitcases. You can also add items locally procured. There are enthusiasts who fabricate their own dolls and accessories.
Generally, when people come to a person's house to see the Golu, they are given prasad (the offering given to God that day), kumkum and a small bag of gifts. These are only given to girls and married women. In the evenings, a "kuthuvilakku" (small lamp) is lit, in the middle of a decorated "kolam"(Rangoli), before the Golu and devotional hymns and shlokas are chanted. After performing the puja, the food items that have been prepared, are offered to the Goddesses.
Golu is adorned with dolls - predominantly with that of the Gods and Goddesses depicting mythology. It is a traditional practice to have at least some wooden dolls. There should also be a figurine of a boy and a girl together. On the 9th day (Saraswati Puja), special pujas are offered to Goddess Saraswati - the divine source of wisdom and enlightenment. Books and musical instruments are placed in the puja and worshipped as a source of knowledge. Also tools are placed in the pooja - as part of "Ayudha Pooja". Even vehicles are washed and decorated, and puja performed for them.
The 10th day, "Vijayadasami" - is the most auspicious day of all. It was the day on which evil was finally destroyed by good. It marks a new and prosperous beginning. New ventures started on this day are believed to flourish and bring prosperity. Kids often start tutoring on this day to have a head start in their education.
In the evening of "Vijayadasami", any one doll from the "Golu" is symbolically put to sleep and the Kalasam is moved a bit towards North to mark the end of that year's Navaratri Golu. Prayers are offered to thank God for the successful completion of that year's Golu and with a hope of a successful one the next year! Then the Golu is dismantled and packed up for the next year.