Abstract
<jats:p>This literature review explores the main theoretical approaches, models, challenges, and emerging trends associated with the internationalization of SMEs and startups. This chapter looks into the classical contributions such as the Uppsala Model, network theories, and institutional perspectives, comparing and complementing them with contemporary phenomena such as born global, process niche firms, and other relevant topics such as entrepreneurial ecosystems, digital transformation, and the impacts of artificial intelligence. This investigation also incorporates a contextual analysis from different countries views and approaches on the SMEs and startups, highlighting structural, institutional, and cultural variations that influence the pace and nature of the internationalization processes. In an integrated manner, the study aims to demonstrate that the internationalization of SMEs is a dynamic and multivariate phenomena, influenced by internal capabilities, resources, technology, networks, and contextual specificities, thus requiring a plural and evolutionary theoretical approach.</jats:p>