Background. The aim of this study is to make a critical analysis of the different definitions of health literacy to provide a framework of the concept. Methods. A literature search was conducted in PubMed, Embase, PsycINFO, ERIC, Health Evidence, Centre for Reviews and Dissemination and Cochrane Library. Google and OpenGrey were searched to find additional papers and unpublished works. Results. Among 7000 papers founded, we selected 26 works. During the 1990s, authors began to systematically study the relationship between health literacy and health status, according to a public health view. In the first decade of the new century, a new fundamental definition established three progressive degrees of health literacy: functional, interactive and critical health literacy. Sørensen (in 2012) provided a framework for the development of new assessment tools and interventions. Conclusion. The improvement of health literacy is a powerful tool for the development of a new type of relationship between individuals and the health system.