Shab-e-Qadr or Layla tul Qadr "the most esteemed of all nights" is a night hidden in the 5 odd-numbered nights of the last ten days of Ramadhan. That is, the eves of 21st, 23rd, 25th, 27th and 29th days of Fast. We are asked to search for it in these nights by staying vigil all night in devotion and prayers. There are several hints to recognise it.
It is the night in which the Holy Quran was first revealed in its entirety to Angel Gabriel (the leader of all angels). The night is so esteemed, as told in the Quran, that we will never be able to fully comprehend its true worth. It is better than a 1000 months, and devotion in which will invoke such divine blessings as we may have never even imagined. Quran further reveals that Angel Gabriel descends on earth with an army of soldiers who spread across the globe and distribute Allah's good tidings to all those Allah is pleased with. The whole night till dawn is full of blessings, peace and benevolence.
The exact night of Shab-e-Qadr is hidden behind veils for reasons best known to Allah. It may be so to have us endeavour to get it as we humans are prone to take all things that are got easily for granted, or because the night is so esteemed that we have to earn it, or perhaps to have us realise its value and of the many of His boons in our life.
Many scholars and experts have even tried to arrive at its exact date based on many calculations and hints got from various Hadiths, and it is popularly believed to be the 25th or 29th eve of Ramadhan. It cannot be said with certainty though, but those who value it love to search for it throughout the five nights of vigil.
There is also a hadith where the exact date was revealed to our prophet Mohammed (peace be upon him) after several nights of pleading he spent before the Almighty. But just as he came out of his chamber to reveal it onto us he saw two muslims fighting over a petty issue. Our prophet was so heart broken by it that he retired to his chamber and Allah too was so displeased that He made our prophet forget it, and took the knowledge of the night back under veil, never to be revealed again. This incident shows us how dear peace, harmony and brotherhood is to our Almighty and his prophet and how unpleasing feuds, fights and warfare are.
Think how displeasing the present scenario of the world would be to our dear Almighty, where jealousy, greed, enemity, feuds, fights, warfare and revenge have become the norm and human life just has no value in the eyes humans at all!