The jalapeño is a medium-sized chili pepper pod type cultivar of the species Capsicum annuum. A mature jalapeño chili is 5–10 cm (2–4 in) long and hangs down with a round, firm, smooth flesh of 25–38 mm (1.0–1.5 in) wide. It can have a range of pungency, with Scovill heat units of 3,500 to 8,000. Commonly picked and consumed while still green, it is occasionally allowed to fully ripen and turn red, orange, or yellow. Mature jalapeños exhibit small cracks around the shoulders of the fruit. It is wider and generally milder than the similar Serrano pepper.
Red jalapeño is the same pepper, just a green jalapeño is picked early in the ripening process, while a red jalapeño is left on the vine to mature. During the ripening, jalapeños, like other chilies, turn red. The additional ripening on the vine means more capsaicin in the pepper itself. The longer a chili has to mature, the more of these healthy compounds they have. So a red jalapeño, with its increase in capsaicin (known for great health benefits), vitamins, and antioxidants, is going to have some added health benefits compared to the green versions.
The name jalapeño is Spanish for "from Xalapa" (also spelled Jalapa), the capital city of Veracruz, Mexico, where the pepper was traditionally cultivated. The name Xalapa is itself of Nahuatl origin, formed from roots xālli "sand" and āpan "water place".
There are many different varieties of jalapeño pepper. They differ in spiciness, shape, size, color. Holy Mole, Jalapeño Sweet, Jalapeño TAM, Giant Jalapeño, Farmers Jalapeño, Jalapeño M, Jalapeño Craig's Grande, Jalapeño Conchos — to name a few.
Chipotle Pepper — a smoked and dried jalapeño pepper.
Read about Health Benefits of Jalapeño Peppers and Benefits Of Jalapeños