The curd is the normal usage of Yogurt in many places. In fact, when milk gets into contact with some acidic substance, it gets coagulated forming curdling, which is used in the preparation of cheese. Instead, when milk is boiled and cooled to a lukewarm temperature and some curd is added to it, that would result in the formation of Yogurt, which is often addressed as Curd.
The yogurt or curd, as most of them mention, is formed by the bacterial fermentation of milk. The fermentation of lactose by the bacteria called “yogurt cultures” produces the lactic acid, which helps in the formation of Yogurt. The culture of bacteria called “Lactobacillus delbrueckii” which produces this yogurt or curd.
Milk is made to boil
Boiled milk is allowed to be cooled to a lukewarm temperature
A spoonful of curd/plain yogurt is added to that milk and mixed well
Let it be there untouched for 5-6 hours to get a perfectly made curd/yogurt
In case, it is not done properly
Take a large container and pour hot water in it.
Place this yogurt bowl in that container. It should float, but not get immersed.
Place a lid on this large container and leave for an hour.
This indirect heating gives the required temperature suitable for the bacteria to grow and form the curd.
Placing a red chilly in the yogurt bowl, during this process will also help.
This can be beaten and made into Lassi or buttermilk by adding some water. The hard formed yogurt is mostly enjoyed with fresh fruits chilled.