A Logo Design can be more than just a recognisable symbol as a logo is also a visual form of communication. A logo can carry a message and communicate this message to an intended market. This message could simply be about the service being offered, for example an estate agent may have a visual reference to properties but a logo can also communicate in various other ways. One such example is the typography used for a logo which can also communicate the nature of the business. An example of this would be an I.T company using a very modern style typeface whilst a traditional furniture maker may use a far more traditional style of typography.
There are also other messages that can be carried within a logo such as the company ethos. A good example of this would be a business that provides a particular service but also has a strong environmentally friendly company ethos. A logo could then also incorporate this environmentally friendly theme into the design to communicate something meaningful about the company.
This is not to say that all logos should communicate lots of information about a business but it is a nice idea to be able to incorporate something meaningful. The most important factor though is that the logo is recognisable and appealing to a particular market.