The interactive, single-user format of personal computers has spawned applications quite different in character from mainframe applications. Like mainframes, personal computers can serve the needs of an organization in areas such as accounting, billing, or inventory. Unlike typical mainframes, however, they also serve personal needs, such as preparing memos, developing financial projections, and planning projects.
Two of the three major personal computer applications--spread-sheets and word processing--are primarily used as personal productivity tools by individuals. The third major application--database management systems--is different. It is used almost exclusively as a scaled-down version of its mainframe counterpart. Mainframe database management systems do not typically serve the individuals needs, but rather the organization's needs.
Does this mean that individuals do not need to store, organize, retrieve, and otherwise manage information? No, they certainly do. But their needs--and the character of their data--are quite different from organizational needs and data.
In the course of their activities, professionals and managers encounter a variety of information that can be conveniently expressed as a short piece of text, that we call an item. An item might represent (for example) an idea, task, reminder, or fact. Typically, an item consists of a single phrase or a sentence and has little or no formal internal structure.
Some examples of items are:
An individual may handle several items in a single day and have hundreds or even thousands of "active" items that need to be stored, organized, and scanned regularly.
While much of the information that individuals need to manage is short and self-generated, sometimes the granularity is larger and comes from other sources. An individual may need to index or organize larger bodies of text such as memos, reports, messages, or news stories. it is useful to associate such objects with items ' where the item may be a topic, summary, source, or headline describing the text. We call such bodies of text notes.
To cope with the task of organizing items and notes, individuals group them into sets--typically in the form of an ordered list or file. The items/notes then can be manipulated conveniently as a unit. We call these sets categ