Chillies come in every colour: green, yellow, red, orange, brown, even almost black. They also come in every shape and size. The poblano is big and gentle. The jalapeño is the famous green one. The chipotle is a jalapeño that's been dried and smoked. The habanero is small, orange and very, very hot.
The 'hot' feeling isn't actually heat - it is a chemical called capsaicin in the chilli that tricks your tongue into thinking it has touched something burning. Birds can't feel it at all. That is on purpose: chillies want birds to eat them and fly the seeds far away.
Each Mexican region has its favourite chillies. Mexican cooks use them to make moles (rich sauces made from many ingredients mixed together), salsas, soups and stuffed dishes. A famous dish called chiles en nogada is stuffed poblano peppers with a creamy white sauce and red pomegranate seeds - the three colours of the Mexican flag.
Chillies have travelled the world. They are now used in cooking in India, Thailand, China, Korea, Italy and beyond. But every single one of those dishes - curry, gochujang, paprika - traces its chilli back to a plant that grew first in Mexico.