Designing professional user interfaces is not only a matter of a good graphic artist and some good ideas. Unfortunately, people creating user interfaces just go for a product, without even being aware of the basics or the theoretical principles behind it. Tight schedules, misconceptions (something like "usability is a plus that we cannot afford now"), and inadequate professionalism are responsible for the poor products that surround us. This article may seem a bit too abstract at first, but its main purpose is to popularize some topics too often limited to academia and few professionals. Here we won't get into the details of some of the many approaches to UI design, because from my personal experience I discovered that people often get absorbed by the "things to do" for building effective user interfaces, rather than catching some simple concepts that will inspire them in the very process of UI design.

This and the next article are mainly addressed to developers or graphic designers who mean to (or are called to) create high-quality user interfaces (UI). Designing a user interface may seem a simple and side aspect of the whole application; in fact it is, perhaps, the most important part of the whole system. Despite our focus on software systems, many of the considerations exposed here can be applied to any human artifact intended to interact with other human beings. This is an important aspect often overlooked. Positive, smooth human-machine interaction is just a matter of good design, as any other product created by people to be used by other people. It is a complex problem, quite different from typical engineering challenges, in that, people (with their own characteristics, emotions, and so forth) are involved throughout the whole process (from designers and developers to end-users, indirect user, and so on).