Pick a deity and it gives the vrat kept for them, step by step: the vrat day, whether the fast is nirjala or phalahar, the sankalpa, the morning and evening puja, the mantra, the katha and aarti to read, the paran, and what may and may not be eaten. Thirteen vrats are covered, from Somvar and Ekadashi to Karwa Chauth. The story itself is on Vrat Katha; this page is the how-to.

Nirjala means without food or water - Karwa Chauth and Nirjala Ekadashi are kept that way. Phalahar allows fruit, milk and the non-grain fasting foods, and is what most vrats prescribe. The page states which one applies to each vrat, since keeping the wrong kind is the commonest mistake.

Fruit and fruit juice, milk, curd, paneer, ghee, sabudana, kuttu and singhara flour, samak rice, makhana and dry fruit, potato and arbi cooked with sendha namak. Kept out: all grains and pulses, ordinary salt, onion and garlic, non-vegetarian food, alcohol and heavy spices.

It is the vow that begins the vrat - water, akshat and a flower in the right palm while you state your name, the vrat, its count if it is a series, and your prayer, then release the water. It matters because the tradition treats the vrat as binding from that moment, which is why a series should be counted and finished.

Breaking the fast, and it has its own timing. Most day fasts are broken after the evening puja with a single sattvik meal; Ekadashi is broken on the Dwadashi morning within a set window; Karwa Chauth after moonrise; Sankashti after moonrise. The prasad is taken first, then the meal.

Children, the elderly, pregnant women, and anyone unwell or on medication - they keep a simple fruit-and-milk fast, or none, and lose nothing by it. A vrat is devotion and restraint, never harm to the body, and a waterless fast in summer heat is a real risk rather than a greater merit.