Which red pepper ingredient does Wikipedia list for Pad Thai?

Wikipedia lists red chili pepper as a Pad Thai ingredient. It may be mixed into the dish or provided on the side as a condiment, giving diners control over the heat and adding a bright, fresh pepper flavor.

The wording matters because Pad Thai is not defined by one fixed level of spiciness. Many versions balance tamarind, sugar, fish sauce, lime, and peanuts, while red chili can be added according to taste. Some recipes use dried chili flakes or other preparations, but the named ingredient in the question is red chili pepper.

Red chili pepper is often confused with black pepper or Sichuan pepper because all can contribute pungency. They are botanically and culinarily different: chili peppers belong to Capsicum, black pepper comes from Piper nigrum, and Sichuan pepper is the husk of plants in the Zanthoxylum genus. Bell pepper is also a Capsicum, but it is mild rather than the conventional hot red chili condiment.