Ageism is a type of discrimination characterized by negative social representations of old age and aging, with prejudices and stereotypes that cause rejection and marginalization of older adults, generally considering them as fragile and unproductive. For this reason, it is recognized as one of the main enemies of healthy aging, especially when it arises from the scientific and professional fields. In this sense, the proposals promoted by some researchers regarding the World Health Organization (WHO) classifying aging as a disease goes against the healthy aging approach. In this sense, we consider that there is no theoretical or scientific support to classify aging as a disease, so we must advocate before the WHO so that aging is eliminated within its disease classification codes. In this framework, this review proposes the concept of "hallmarks of ageism" defined as the characteristics, representations and attitudes of rejection and discrimination towards aging, old age and older people, at the political and institutional, scientific or professional, technological and digital, social, family and personal levels, which are presented in an articulated and structured manner. For this reason, it is essential to comprehensively identify and analyze the "hallmarks of ageism", in order to propose programs that include strategies and public policies that promote "anti-ageism" as a counterproposal to the "hallmarks of aging", whose biological changes related to aging are intended to be comparable to chronic non-communicable diseases.