Here is your short paragraph on Satya Narayan Vrat:
This is observed in all parts of India during Sankranti or Purnima of any month in honour of Lord Vishnu or Narayan.
According to a legend, sage Narada, the divine wanderer once visited this earth and was deeply moved by the misery and affliction of mankind.
He then pursued Lord Vishnu (Narayana), who then advised that let the people keep Narayan Vrat on any day as described above, and hear the Katha of Satya Narayan and perform puja, all their miseries would come to an end.
After performing the Puja five stories about the glory of the Lord and his grace are narrated. Violation of the vows taken in, His name brings terrible calamities.
The puja is followed by distribution of Prasadam. In Bengal, a special kind, of prasadam called ‘Sinni’ (a semi-liquid recipie comprising of flour, sugar, milk and coconut) is prepared on the occasion along with the prasadam.