The Thailand 4D lottery is a popular form of gambling in Thailand, although it's technically illegal. It involves matching four numbers. While the official Thai lottery is a separate government-run lottery, the '4D' version operates more informally. Players typically buy tickets from local vendors, hoping to match the last four digits of a drawn number from another official lottery. Due to its informal nature, payouts and rules can vary. It's essential to be aware of the legal implications and risks involved before participating.