15th August is our National Festival Day. Every creature in this universe wants salvation or freedom. We had got the freedom this day, therefore it is important to every indian. Lord Shiva is the bestower of Moksha ( Salvation) to every creature in the Universe thats why Shiv Puja is very important on this day. There is also Som Pradosh (13th Lunar Day on Monday) on this day. This is a special and very important occasion for Shiv Puja. Lord Shiva gets pleased by this Puja.