7 Layer Dip Recipe

There are so many recipes around for 7 Layer Dip that I am totally confused.

What goes into a 7 layer dip?  What order do the layers go in?  Where did this idea come from in the first place?

From Wikipedia:

Seven layer dip is the name of an American appetizer based on common ingredients in Tex-Mex cuisine. The dish typically includes:

1. Refried beans
2. Guacamole
3. Sour cream
4. Picante salsa or chopped tomatoes
5. Grated Cheddar cheese, Monterey Jack cheese or a blend of both
6. Black olives

The seventh “layer” may be one of many items, such as cooked ground beef, shredded lettuce for texture, or jalapeño chiles for additional spiciness.

The dish is often chilled before serving, and is served with tortilla chips.