Raising in the poker is an additional approach to win the game. From a strategic perspective, an opening bet could be considered as a raise. The following are some of the reasons for raising given by David Sklansky:
1. Getting a free card:
If the participant raises the bet with a drawing hand, then, on the following betting round his opponent might check to the player which gives the player a chance of getting a free card for improving his hands.
2. To win a bigger pot:
The player raises when he has the best hand to get a hold of additional money in the pot. Suppose if the player has the best hand, then raising for the value enables him to win