The Internet has expanded beyond the world of desktop computers, and today we can say with confidence that within a few years, devices with small screens will become the leading form of Internet access. Here is the first and only practical guide that answers the question in a step-by-step form , how to make a website as convenient as possible for all its visitors, regardless of what device they will view it on. It contains recommendations on how to avoid the most common mistakes and solve most of the problems faced by modern Internet users. In addition, in it you will find program codes that will allow you to put into practice all the proposed developments.