Urban vitality is the quality of those spaces in cities that are capable of attracting heterogeneous people for different types of activities throughout varied schedules.[1] City areas with high vitality are perceived as alive, lively or vibrant and tend to attract people to carry out their activities, walk or stay. However, areas of low vitality repel people and may be perceived as unsafe.[2][3]​.

The urban vitality index is a measure of this quality and in recent years it has become a fundamental tool for planning urban policies, especially for the intervention of spaces with low vitality.[4]​ In addition, it is used for correct management of spaces with high vitality, since the success of certain areas can lead to processes of gentrification and tourism that, paradoxically, end up reducing the vitality that made them popular.[5]​.

The concept of urban vitality is based on the contributions of Jane Jacobs, especially those of her most influential work, *Death and Life of Great Cities"). Jacobs criticized in the 1960s the modern, rationalist architecture advocated by Robert Moses or Le Corbusier whose protagonist was the private car. He argued that these types of urban planning overlooked and oversimplified the complexity of human life. He opposed large-scale urban renewal programs that affected entire neighborhoods and who built high-capacity roads through city centers. Instead, he advocated for dense mixed-use development and walkable streets, with "eyes on the street" of pedestrians themselves helping to maintain public order.[6]​.

Currently, the concept of urban vitality is revaluing Mediterranean urban planning and its history, in which public space, pedestrianism and squares have great importance as centers of interaction and social cohesion, in opposition to the Anglo-Saxon urban planning of large urban infrastructures, long distances and focused on the automobile.[2]​[3]​[7]​.

Urban vitality can be quantified thanks to the analysis of the elements that determine it. Among them are:[8]​.

• - Diversity of uses of the space that can attract different types of people for disparate activities and at different times, making the space constantly occupied, improving its security.

• - Opportunities for personal contact with blocks, blocks, and open spaces that are not too large, as they reduce the number of possible intersections and social interactions.