What is a poem? What ideas about the poem as such shape how readers and audiences encounter individual poems? To explore these questions, the first section of this Companion addresses key conceptual issues, from singularity and genre to the poem's historical exchanges with the song and the novel. The second section turns to issues of form, focusing on voice, rhythm, image, sound, diction, and style. The third section considers the poem's social and cultural lives. It examines the poem in the archive and in the digital sphere, as well as in relation to decolonization and global capitalism. The chapters in this volume range across both canonical and non-canonical poems, poems from the past and the present, and poems by a diverse set of poets. This book will be a key resource for students and scholars studying the poem.