Information Retrieval (IR), has been part of the world, in some form or other, since the advent of written communications more than five thousand years ago. IR has as its domain the collection, representation, indexing, storage, location, and retrieval of information-bearing objects. Traditionally these objects have been text-based documents such as articles, reports, and books; however, as multimedia computing has progressed, the list of information-bearing objects has grown to include such things as images, videos, maps, sound, and music recordings. In the modern sense of the term, IR has its roots in the scientific information explosion that accompanied, and followed, World War II. Predating the computer, early modern IR systems used ingenious manual mechanisms to deal with the millions of scientific and technological research papers that were being written as part of the war against tyranny.

The remarkable growth in computerization has lead to...