Topic Maps are a new standard for describing knowledge structures and associating them with information resources. A Topic Map is a representation of the information used to describe and navigate information objects. Topic maps are designed to provide powerful ways of navigating through large quantities of information. Topic Maps are also intended to be useful for the management of large information pools. Topic Maps provide a uniform "navigation layer" over a set of information resources, independent of the format of the resources themselves.
Topic Maps are metadata that need not be inside the information they describe, as an external layer is superimposed on the information objects they describe. The primary goal of topic maps is to facilitate the management, organization, navigation and retrieval of information, often from large pools of disparate but interconnected resources.
If you are looking for a particular piece of information in a book, a good index is an immense asset. In the world of electronic information, there has been no flexible equivalent of the traditional back-of-book index. Most indexes remain firmly within the context of a single document and are mostly published on paper.
The world of electronic publishing is quite different from traditional publishing. Information delivery is often component-based and personalized according to individual tastes. The new requirement for indices is that they span multiple document components, to cover a pool of information objects rather than focusing on a single document or book. In this new situation the old-fashioned indexing mechanisms are inadequate and new ways of indexing need to be explored.
One way to address this problem is by making use of full text indexing, a technique widely used in the domain of the World Wide Web. Anyone who has used search engines on the internet knows that full text indexing isn't the answer to the problem of flexible search and navigation. The main problems with traditional full text indexing are the lack of discrimination (they index every single word in a document); the lack of any relationships between index terms; index terms are often meaningless etc.
Topic Maps, a new electronic indexing approach combining the world of traditional indexing with advanced techniques of linking and adressing, are one possible answer to these problems.
One could simply state: just as a traveller needs a map to navigate through the world, a Topic Map helps to navigate through the world of information.