Ekadashi, or Ekadasi, is the eleventh day of a fortnight in a Hindu lunar calendar. The day is dedicated to Lord Vishnu and many devotees undertake Upvaas or fasting on the day. There are two Ekadashis in a lunar month. The date (s) of Ekadashi in March 2008 – March 3 and March 17.
The preparation for Ekadashi fasting begins on the Dasami day – the day before Ekadasi. On the Ekadasi day, devotees observe complete fast. The day is meant for hearing religious discourses and performing pujas.
There are also devotees who do not observe total fast. They avoid grains especially rice and consume fruits, nuts and milk.
The fasting comes to an end on the Dwadashi day with the consuming of food cooked in one’s house.
More on Ekadasi can be found in this article.