Drifting is a driving technique which enables sharper steering in a vehicle.
In exchange for greater tire friction and lower cornering speed, drifting improves the rate at which a car can steer in any direction. On tarmac, drifting is normally a slower cornering method than traditional methods used by professional drivers. In rally racing, however, drifting is an essential technique for many corners (due to rough terrain, which can sometimes require alternative driving methods to achieve higher cornering speeds). Drifting has been available to players since Grand Theft Auto III. But, prior to the release of Grand Theft Auto: San Andreas, drifting did not offer players much car control.
The differences between drifting around corners and driving around corners are best described visually (watch professionals to better understand these differences). When a vehicle drives around a left turn, for example, the driver is steering left. When a vehicle drifts around a left turn, ideally, the driver is steering right. While a vehicle is drifting, it travels around a corner on an angle. The vehicle has lost rear traction and is spinning around, but the driver is preventing the car from spinning around completely. A driver controls this loss of traction through many rigorous throttle and steering corrections, and is "controlling" a vehicle that is trying to spin around. The driver is "spinning out" around a corner, but remains in control of the vehicle.
Grand Theft Auto: San Andreas
In Grand Theft Auto: San Andreas, vehicular handling physics had greatly improved. These revised physics emulated reality well in certain ways. Handbrake deceleration encouraged drifting, turning angles during drifts could be very low or very high, and weight transfer could be used to initiate a drift. Every vehicle had unique characteristics. Vehicles decelerated unrealistically while moving in reverse however, which made performing J-turns or 360 turns impossible without nitrous or speed, or a slope.The sharp deceleration in reverse made “donuts” impossible without nitrous activated. Even the quickest rear-wheel drive cars regain traction when spinning around, unless nitrous is engaged. Nitrous was a limited, purchasable performance upgrade for most vehicles in San Andreas. With nitrous engaged, vehicles accelerated quicker, and decelerated slower. Nitrous improved the performance of cars to a great extent, allowing them to drift with much bigger angle at lower speeds. Utilizing nitrous, a player could perform much longer and faster drifts than otherwise possible.
Many GTA: San Andreas fans with the PC version have developed original handling physics for different cars in the game. These original "handling lines" allow for ease of initiating drifts and prolonging drifts. This is partly achieved by grossly increasing vehicle acceleration, to counter the default physics' low-speed shortcomings. Modding GTA games to allow ease of drifting has become a popular practice.
Grand Theft Auto IV
The completely new handling physics in GTA IV were poorly received. Drifting properly was impossible with the new handling physics. Game-assisted J-turns and 360 turns could be performed with ease, but vehicles felt large and clunky to drive, and were unkind to players who pulled the handbrake. Drifting could be mimicked (poorly) by driving on wet roads or by popping rear tires. To counter the handling physics' shortcomings, players with the PC version of GTA IV have developed original handling physics for vehicles in the game. Drifting in GTA IV is almost exclusively performed through the use of "handling lines."
Grand Theft Auto V
The handling physics system in GTA V is a revision of GTA IV’s system. Vehicles can now corner at much higher speeds, and have greater top speeds. Drifting properly is still impossible, but it can now be well-mimicked at very low speeds. Some players use the single-player cheat “slidey cars” to alter the game’s handling physics system. With “slidey cars” activated, vehicles seem to handle like they are on ice. The “slidey cars” cheat does not make proper drifting possible. Handling lines are now a popular drifting medium on the PC version of GTA V.