Just what is a logo?

For a couple of weeks now, my sis has been bugging  me about designing a logo for her business since she will be opening a shop next month. After some asking, it's not just the logo. It will probably include a website, business cards, etc... I've listed some questions for her about the nature of the business, products and services, what kind of image does she want her biz to project to existing and potential clients, and stuff like that so that I can get a good grasp about what the biz is all about and design a suitable logo. However, seems like my sis has a different idea about what a logo is.

So, what is a logo?

From the net, a logo is:

• a graphical element that, together with its logotype (a uniquely set and arranged typeface) form a trademark or commercial brand (wikipedia)

• a graphic representation of a business or product (ezinearticles)

• your company's most important design element because it's the basis for all your other marketing materials: stationery, packaging, promotional materials and signage (entrepreneur.com)

• a name, symbol, or trademark designed for easy and definite recognition, especially one borne on a single printing plate or piece of type (thefreedictionary)

Well, that's my understanding of what a logo is, also.

What's my sister's idea of a logo? It's something that looks like her multiply site's header image -- complete with pictures and stuff. I've already told her what's on her site isn't a logo but a header image. After makingtwo logo designs, I'm told if I can make something like the one in her multiply site header. So much for designing if I will just copy...

I don't think I'd like to do that layout now if I can't exercise my own creativity...