A logo is the visual representation of a company. The Nike "swoosh" is a good example of a well known logo. The "swoosh" was created in 1971 by Carolyn Davidson, a graphic design student who started doing freelance work for Phil Knights' company, Blue Ribbon Sports (BRS). BRS needed to create a brand for a new line of athletic footwear it was preparing to introduce in 1972. When the idea for the swoosh was presented, Knight's response was "I don't love it, but I think it will grow on me." Knight didn't love the "swoosh" but it came to mean something over time. Was the Nike logo a good logo? It was a clean and simple design and easy to remember. Over time, it became part of a very well known brand. A brand is not a logo, but over time a certain meaning can be associated with a logo. A logo identifies a business in its simplest form via the use of a mark or icon but don't forget that is takes time for a logo to be embraced and how your business operates will have a significant impact:
When your designer presents a logo to you, you may not love it instantly but here are 5 criteria you can use to evaluate it.

Is is easy to describe?

Is it easy to remember?

Does it work well in black and white

Is it scalable? i.e. work when just an inch in size

Is it relevant to the industry in question

Logo design is a true art. Make sure to hire a good designer - one that has had training in a reputable graphic design program. Since the invention of desk top publishing, everyone is a designer. Do your homework.