In tennis, a grip is a way of holding the racquet in order to hit shots during a match. The three most commonly used conventional grips are: the Continental (or "Chopper"), the Eastern and the Western. Most players change grips during a match depending on what shot they are hitting.
In order to understand the grips, it is important to know that the handle of a racquet always consists of 8 sides or, in other words, has an octagonal shape. A square shape would hurt the hand, while a round shape would not give enough friction to gain a firm grip. The eight sides of the handle are called bevels. We can number the bevels from 1 to 8 as follows: if the blade of the racquet is perpendicular to the ground, the bevel facing up is bevel #1. Rotating the racquet counter-clockwise (for a right handed player, clockwise for a left handed player), the next bevel facing up is bevel #2, if you are right-handed, and clockwise if you are left-handed, and so on to identify all 8 bevels.
The Continental grip, also called the Chopper grip or Hammer grip, is obtained when placing the hand such that the base knuckle of the index finger is right on bevel #2. It is naturally obtained when holding the racket as if it were an axe, hence the second name "Chopper grip". The Continental grip is suitable for a variety of shots and therefore is often taught to absolute beginners, so that they should not bother changing grips while learning the basics of the game. This type of grip is very useful for quick volleys and strokes near the net. Since modern tennis, especially clay-court tennis, has shown an evolution towards topspin, the Continental grip has gone out of fashion with professional players for hitting groundstrokes. It is still the preferred grip for serves and volleys. Additionally, the grip is used for some defensive strategies, such as chipping and blocking shots. Moreover, the grip can be used offensively to hit a "drop shot", which puts extreme backward spin on the ball. The rest of the grips strike a balance between high spin capacity on the one hand, and power on the other.
The Eastern Forehand grip is obtained when placing the hand such that the base knuckle of the index finger is right on bevel #3. The Eastern Forehand grip allows for fast, flat shots on the forehand, with some control through topspin. Net players like it because it easily changes to the continental grip for volleys. It offers little control at high balls, and there is not enough control to sustain long rallies. It is also known as the shake hands grip.