Types of Peppers
There are as many pepper types as can grow wild and thrive wild in different parts of the world. Here's an assortment of the most commonly available in American markets:

Anaheim: see New Mexican chile.

Ancho: see Poblano.

Banana pepper (0 to 5): Pale yellow-green to yellow (maturing to bright red); it's about 6 inches long, a fat finger, that tapers to a point. Aka, Hungarian wax, when it's hot.

Bell pepper (0): A big chambered sweet "box" that comes in green (unripe), yellow, red, orange, brown, and purple...but mostly green in the stores.

Cascabel (hot, 4): A cherry- or mushroom-looking thing, 1 x 1 inch, that's mostly used in dried, ground form. When it's dry, the seeds rattle around, making it "cascabel" or "jingle bell."

Cayenne (plenty hot, 7-8): A dark green or red--and bony, skinny witch's-finger looking thing with a pointed end. Usually about 5 inches long, 1/2 inch in diameter.

Cherry (sweet to hot, 0-4, 7-8): Medium green to red, thick fleshed, and shaped like a big cherry (running from 3/4 inch to an inch and a half).

Chilaca : see Pasilla.

Chiltpin or Chiltecpin or Pequin or Thai bird peppers (very hot, 8-9): These 1/4 x 3/4-inch oval peppers are glossy and range from red to green to nearly black. They make a good kitchen plant: you can mash these little guys into soups and salad dressings--or you can pickle them in vinegar in a little kitchen counter bottle and spritz the vinegar into the soups and sauces.

Chipotle: These can be any pepper, but dried by smoking. Jalapenos are commonly made into chipotles.

Cubanelle (sweet, 0): Pale yellow-green to orange to red, sometimes a mix of all three. They're glossy, long cylinders with defined seams and a sunken, inverted end point. They are thick fleshed and more flavorful than bells--a classic wax type.

Datil (very, very hot, 10): One of the capsicum chinense peppers that will blow the top of your head off. They're wax types, shaped like baby fingers (2 x 3/4 inch)--a little wrinkled and pointed at the end. Generally yellow green to golden yellow.

De Arbol (hot, 7): green to red colored, 3 x 3/4 inches, shaped like skinny fingers with a very pointy end. Usually found dried and whole in packages.

Fresno (hot, 5-7): Yellow-green to red, these glossy cones are about 3 inches long, an inch and a half at the base. A thick wax type that's only used fresh because its too fleshy to dry properly.

Guajillo (dried) / Mirasol (fresh) (hot, 4-5): Truly variable--it can be little or big, smooth or wrinkled. Generally, it's green to red (red brown, dried), peapod shaped with pointed ends. Its thin skin makes it excellent dried--as which it both flavors and colors dishes beautifully and in small quantities.

Habanero (whew--10+): Beautifully colored (green, yellow, orange, and orange red) and shaped like lanterns, with points at the end, they have completely distinctive aromas and flavors. They're smallish, 1-2 x 1-2 inches, but pack a huge punch. Originally from Yucatan, they're associated with Cuba--"from Havana." They're in the capsicum chinense family.

Jalapeno (hot, 1-5+): Bright green to black green, maturing to red, this is found in most supermarkets. It's smooth, thickfleshed, sometimes blistered. When marketers found out people picked blistered-looking jalapenos over smooth ones, they cultivated ones with blisters. No taste difference whatsoever. Jalapenos are generally shaped like big Christmas tree lights, including their blunted pointy end. They're named for the Mexican city of Jalapa in the state of Veracruz.
NOTE: When smoked, jalapenos are called chipotles.

Mirasol: see Guajillo.

Mulato: see Poblano.

New Mexican Chile, AKA Anaheim (mild to hot, 1-4): Bright green to red when fresh; brownish red when dried. This long (7-10 inches), thin-skinned flat tube tapers to a blunt point. It's probably best known as the chile of choice for stuffed rellenos. It traveled from Mexico to New Mexico in the late 16th century--then moved made a historic move 300 years later with Emelio Ortega to his California ranch. Ortega made such a commercial go of it that it became known as an Anaheim, despite New Mexico's steady cultivation and improvement of the pepper. When scientists of the National Pepper Conference recently called for a new name designation for the type, New Mexicans girded their loins and did not stop crusading until it was recognized in the Congressional Record as the "New Mexican chile type."

Pasilla (dried)/Chilaca, fresh (medium to hot, 3-4): "Pasilla," meaning "little raisin," looks just like that--warm black and wrinkled--but long (6-12 inches) and skinny with a pointed end. In its fresh form, "chilaca," or "old-looking," also fits, as it's also wrinkled and bent--but it's chocolate colored from the green chlorophyll sustaining itself into the mature stage when red pigments are produced. Don't confuse these with mislabeled anchos and mulatos--and enjoy the mellow flavor.

Pequin, see above under Chilpin.

Pepperoncini (sweet to mild, 0-1): Most often found green, pickled, and in salads, this 2- to 5-inch-long pointy tube is wrinkled, thin-fleshed, and can be grown in a home garden to a red color.

Pimento (sweet, 0): Heart-shaped and thick-fleshed, this glossy chile ripens from green to red and grows to about 4 inches long. It's got a nice mellow flavor and is great for adding color.

Poblano (fresh); Ancho and Mulato, dried ( both are mild to hot, 3): The fresh Poblano is a 4-inch-long dark green (ripening to dark red or brown) cone that tapers to a blunt end. It's flesh is undulating and nicely thick. It gets its name from the city of Pueblo, Mexico, where it is a chile of choice--and often used as a relleno shell. It has two dried forms. The "Ancho" is dark brown, which turns brick red after soaking (don't soak it more than an hour...and save the juice to spice soups). The "Mulato" is dark brown that stays brown after soaking--and it has a sweeter, richer, and hotter finish that has also been described as chocolatey.

Rocoto (worse than habanero, 10++): This capsicum pubescens is a fireball of unbelievable proportions. Generally not available outside of Latin America, since its fragile fruit is grown only in high altitude, cool climates, it comes in green, yellow, and red globes, about 2 x 2 inches, and has a hairy stem.

Sante Fe Grande (medium to very hot, 6): This glossy wax-type pepper comes in pale greenish yellow, orange, and red and looks like big Christmas tree lights--with smooth, thick flesh, about 3 inches long. Very similar to the Fresno pepper.

Scotch Bonnet (habanero hot, 10+): A lot of people think this capsicum chinense IS the habanero, but it's not. The big difference between the two is the tip: the Mexican habanero is pointed; the scotch bonnet (from the West Indies) is deeply inverted with a distinctly round bottom--thus making it look like a tam o'shanter with a great big pompom. It comes in green, yellow-orange, and orange.

Serrano (hot to very hot, 6-8): These glossy green/red tubes are about 2 inches long and blunted at the end. Their name comes from serranias, meaning "foothills," because they're believed to have originated in the foothills north of Pueblo. They don't have to be seeded or peeled--and they have a fresh, crisp finish.

Tabasco (very hot, 8-9): These little pointy tubes are about 1-inch-long and come in pale yellow-green to yellow to orange to red. A capsicum frutescens pepper, it was commercially developed into a hot pepper sauce by the McIlhenny family in Louisiana--and soon took on the name of the sauce itself. To this day, the McIlhenny family fiercely protects its rights to that name.

Thai bird peppers, see above under Chiltpin.

Tomato pepper (sweet, 0-1): This 3-inch pepper is shaped like its name and is thought to be the precursor of the bell pepper. It's thick-fleshed, comes in green and red, and is best known red as a primary source of the spice paprika, in its powdered form.