The Bid is the minimum selling price = Bid, and Ask is the maximum purchase price = Demand.
Bid = purchase price of the market to which the investor sells.
Ask = selling price of the market to which the investor buys.
When an investor wants to take long positions in the market must be set in the Ask price will be the order is executed if the market launches and instead an investor wants to sell the position will close the Bid price.
The alternative to these executions are limit orders, which allow entering intermediate values to try to make better market positions.
For this reason it is the fork against fewer, better entries and exits will occur, improve outcomes, to recover before the cost of execution and start seeing positive position.
The forks are less than greater number of negotiations that occur in a particular underlying, which will provide more liquidity and more competitive prices.
Keep in mind that just entering the market money is lost by the fork or also called spread, although the starting order instantly lose the difference is executed.
Forks and spreads show the liquidity of the underlying, against more tight is more investors are trading the securities at those prices.