Conference given at ParisWeb by Eric Gateau and Elie Sloïm on October 10, 2019 In 2000, the analysis of the headings of a directory of links dedicated to the quality of the web led us to produce a 5-point model. This model, called VPTCS, for Visibility, Perception, Technique, Content and Services was published on October 25, 2001. It is now almost 18 years old. On this occasion, and as it is increasingly used by professionals, we wanted to take stock of its genesis, development and uses. During this conference, we will present the method that led us to its conception. We will see to what extent it allows us to describe the fundamental elements of the user experience. We will show you how it allows us to describe the evolution of the web sector, through the notions of UX and UI, the role of ESNs and web agencies, the responsibility of site buyers on the final quality of sites, and many other aspects that structure our business. We will also see how the model could evolve in the near future.