Question about stop loss

General
1

i have heard about the stop loss fixation along with the target price.
when we use say, for example, i am using bracket order leverage futures of the following
reliance industries limited: buy price:1400
target price: say, 1450
stop loss:1350

now, some people like to place the distance between stop loss and target price equal to the bid price and ask price difference.
my question is:

  1. what is bid price and ask price.
  2. does it really makes sense to put the stop loss and target difference equal to bid-ask spread?
  3. what advantages does it have over the normal last support based stop loss and
  4. does the bid -ask spread difference is equal to the lower and upper circuit price difference?
2

Check section 9.6 here - http://zerodha.com/varsity/chapter/the-trading-terminal/

  1. Not sure, sometimes the difference between bid and ask can be too tight and does not make sense

  2. Nothing really

  3. No.