Language portfolios is an academic concept and pedagogical tool utilized in language education. It encompasses a collection of a language learner's work, self-assessments, and reflections, providing a structured record of their linguistic and intercultural development over time. As a research domain, it investigates the processes of language learning, learner autonomy, and self-assessment facilitated by portfolio creation and maintenance, examining their impact on proficiency development and assessment practices. Key characteristics include its learner-centered, reflective, and developmental nature, often aligned with frameworks for describing language proficiency. Its significance lies in promoting learner agency, offering a comprehensive, longitudinal perspective on language acquisition and use, and serving as a versatile instrument for both formative and summative assessment, as well as the formal recognition of language competencies.