The objective of this article is to conceptualize Echo Chambers from a literature review and to present its methodological implications for studies on the political public sphere in social network platforms. An echo chamber is a social epistemic structure in which relevant voices are actively excluded and discredited by creating ambiences of homophily. This homophily is shown when users of social networking platforms interact and associate only with similar ones, with selective exposure to content. It is associated with processes of evasion, questioning and constant search for reinforcement. This translates into the tendency to consume information aligned with previously constituted ideologies only with confirmation bias, and in the propensity to seek, choose and interpret information aligned with one's own belief system, including news that does not match reality. We conclude that it is important to untangle algorithm and user in strategies that consider the dimensions of platform technology, the communicative process of conversation and deliberation, and its concrete effects in the political sphere. Another important factor is the identification and objective delimitation of which are the homophilic patterns present in certain groups on the platforms