Bluffing is an important part of most poker player's games. Knowing when and how to bluff will dramatically increase your win percentages. Semi-bluffing is an extra weapon for your Texas Holdem poker armoury. The differences between bluffing and semi-bluffing :
Bluffing is defined as an act of deception by a false show of confidence in strength of your cards. Basically, you're trying to convince your opponents that your hand is unbeatable. When you choose to bluff, you're actually hoping that everyone else folds. If anyone calls you'll be on losing end of round.
However, Semi Bluffing falls between normal betting and bluffing. A Semi buff is very similar to a bluff, only difference being that you can still make a winning hand. So if someone calls your semi-bluff you can still find last card to make a winning flush or straight.
When to semi-bluff: The best time to semi-bluff is if you have to good hand that is only one card away from being an almost unbeatable hand. You'll play a semi-bluff before river, leaving open possibility of picking up an extra card that should win it for you.