It is a century old tradition for us to eat in Banana leaf.
In Tamil language, the words "Banana leaf" is formed by "Vazhai" + "Ilai"
"Vazhai" means Banana
and "Ilai" means Leaf
Please note this is not eating the leaf itself but use the leaf as a plate to eat. This practice is not only common in Tamil Nadu but also in all South Indian states of India Andhra, Karnataka and Kerala. Eating in Banana leaf can be found in other countries like Singapore, Malaysia, Sri Lanka. In Thai and Vietnamese cuisine there are some food wrapped in Banana leaf and cooked.
In day-to-day life, you can see people eating in a Banana leaf in country side. Typically there is a plantain tree in their backyard. They will just cut a leaf and serve food on that banana leaf.
Banana leaf in our backyard
When there is guest at home, then food is served in a Banana leaf.
Most of the restaurants in Tamil Nadu, serve meals in a Banana leaf.
You can see similar tradition in South Indian restaurants globally. For example: In Singapore, Malaysia and Sri lanka serving Tamil meals in Banana leaf is a common sight.
In general, eating in Banana leaf is common during festivals and auspicious days.
Other names/spelling variations of Banana leaf:
Just "Ilai" or "Elai" in Tamil language also means Banana leaf
Vaazhai elai, Vazhai ilai