Circuit breaker system of Share Market

Today I wake-up around 10:30 am morning and open TV, 1st news which attracts me was 'Circuit Break: Sensex hits upper circuit for the first time in the history of the bourse' (based on my memory). Honestly speaking, I didn't understand these lines. In simple word I understand that there is some interesting hike in share market.
I hope you all agree that if you have seen some thing in morning that remains in your mind for whole day (Especially songs, it happens with me). This word (Circuit Break) was knocking in my mind after every few hours whole day. And Questions are very simple.
What is Circuit Break? How its work on Share Market? What will be outcome of this? What is reason of this? Etc...
I solve my last question (What is reason of this) in morning itself as News Channels were showing in morning that Market is happy with formation of a stable government at the Centre. In some Interview I heard that there will be no LEFT party in Govt this time for leg pulling and some other stuff. Like Manmohan Singh is big shot in terms of his knowledge about Economy.
There are several lines like in Hindu(News Site) it was written: Brokers said investors were strongly optimistic about consistent and substantial increase in capital inflows in the future as economic reforms are likely to get top priority after Manmohan Singh becomes Prime Minister for a second term.
Now 1st Question, What is this Circuit Break in Share Market:
Circuit breaker system, is an index-based system that would halt trading at three stages
— If the Sensex or NSE S&P CNX Nifty fluctuate
1) More than 10 per cent.
2) More than 15 per cent
3) More than 20 per cent
On any day during a quarter.
Circuit breakers will bring about a co-ordinated trading halt in all equity and equity derivative markets across the country. The decision follows a direction from the Securities and Exchange Board of India.
2nd Question How it works:
1) When market flacuate more than 10%: In case of 10 per cent movement of either of above indices before 1 p.m., there would be a one-hour market halt.
In case the movement takes place at or after 1 p.m. but before 2.30 p.m., there would be a trading halt for half an hour.
In case the movement takes place at or after 2.30 p.m., trading would not be stopped at the 10 per cent level.
2) When more than 15 %: If either index moves more than 15 per cent, there will be a two-hour market stop if it is before 1 p.m. And a one-hour halt if it is on or after 1 p.m. but before 2 p.m. Trading will be stopped for the rest of the day if the trigger is reached at or after 2 p.m.
3) When More than 20%: Trading would stop for the remainder of the day if either of the indices moves 20 per cent or more.
Note: Percentages are calculated on the closing index value of the quarter. These percentages are translated into absolute points of index variations (rounded off to the nearest 25 points in case of Sensex). At the end of each quarter, these absolute points of index variations are revised and made applicable to the next quarter.

On March 31, 2009, the last trading day of the quarter, Sensex closed at 9708.50 points. The absolute points of Sensex variation (over the previous day's closing Sensex) which would trigger market wide circuit breaker for any day in the quarter between 1st April 2009 and 30th June 2009 would be as under:
Percentage (+/-) Equivalent Points (+/-)10% 975
15% 1450
20% 1950
This is the first time that trading halted within seconds of the opening bells with the Sensex and Nifty soaring by 15 per cent and again by more than two per cent after the market re-opened at 1155 hours as market participants turned extremely bullish after the Congress emerged as the single largest party in the Lok Sabha elections.
NSE index Nifty surpassed the first 10 per cent upper limit in just 13 seconds and even crossed 15 per cent limit, resulting in suspension of trading for two hours.
Hope this help you to understand this Term, and you don't have to confuse whole day like me :(.