Tailgating has two different meanings. The first meaning refers to the action of a driver driving behind another vehicle while not leaving sufficient distance to stop without causing a collision if the vehicle in front stops suddenly. The second meaning refers to a social event held on and around the open tailgate of a vehicle, which primarily takes place in the United States and Canada. Here are some more details about each meaning:

Tailgating while driving:

• Tailgating is illegal and can be dangerous to the tailgater, especially if they are driving closely behind a large vehicle (such as a tractor-trailer, or gas tanker). By tailgating, the driver has a shorter distance to stop, decreases the margin of error and blocks the awareness of surroundings.
• Tailgating can occur when a vehicle attempts to prevent another vehicle on the right or left from cutting in front of them. The tailgating (or preventing) vehicle will drive as close as possible to another leading vehicle to prevent the side vehicle from cutting in. This practice of tailgating is illegal and attempts to force the side vehicle to slow down and get into the line of traffic behind the tailgating vehicle.
• Tailgating may occur when the drivers of two vehicles do not want to be separated, the vehicles are in a procession (e.g. funeral), or the vehicles are maintaining a formation for security purposes (e.g. escorting a dignitary or a dangerous prisoner) .

Tailgating as a social event:

• A tailgate party is a social event held on and around the open tailgate of a vehicle. Tailgating often involves consuming alcoholic beverages while barbecuing and grilling food. Tailgate parties occur in the parking lots at stadiums and arenas, before and occasionally after games, festivals, and concerts.
• Tailgate parties also involve people bringing their own alcoholic beverages, barbecues, and food, which are sampled and shared among fans attending the tailgate. Tailgates are intended to be non-commercial events, so selling items to the fans is frowned upon and can even be considered illegal soliciting.
• Tailgate parties have spread to the pre-game festivities at sporting events besides American football, such as basketball, hockey, baseball, and soccer. They also occur at non-sporting events such as weddings, cultural festivals, and concerts.

If youre following another car too closely and the car in front of you stops suddenly, its important to maintain a safe driving distance to prevent accidents.