Corsets are some of my favorite lingerie. They help to create an exaggerated feminine shape. You may not realize it but there are actually two different types of corsets: those with steel-boning, and those with plastic boning. Steel-boned corsets retain their shape over time, and are more expensive than the cheap one-off corsets found in lower end retail stores. The tube top, flimsy corsets are referred to corset tops. They look like a corset, but they don't act like one.
There are also a few different styles of corsets out there: your traditional strapless, with lapels (as seen above in my custom-made corset by Dolly Donshey of Monstruosite), or an under-bust corset. Underbust corsets are definitely more versatile as they can be worn over a dress or a shirt.
Overbust corsets are perfect for the more endowed Betty, while those with more petite measurements benefit from flat-front corset. Long-line corsets hide a full belly quite nicely while straps can help disguise wide shoulders. See, aren't corsets lovely?