Traditionally, much of the efforts to develop computer-based tools has been concentrated on developing production or authoring tools, such as word processors, drawing programs, and so on, and not so many consumption or reading tools have been developed except Web browsers and different kinds of media players. Authoring plays an important role in the learning process, and good tools are needed, but reading—especially active reading—and exploring are is at least as important. Traditionally, computer-mediated texts have little support for an active way of reading. This means that reading computer-mediated texts, as on the WWW, tends to be a very passive form of reading. The development of Text-Col addresses this problem. Text-Col is a tool designed to support readers in deep processing of texts by letting the readers change appearance of the text based on different strategies for categorizing words. Text-Col is a reading tool and exploring tool aimed to make the reading process more active.