metals (or topological matter) are to a large extent interfacial processes.(iii) Interfacial Dzyaloshinskii-Moryia interaction drives the creation and manipulation of skyrmions in ultrathin magnetic layers.(iv) Systems based on the interface between superconductors and topological insulators are considered to be possible routes to observe the elusive Majorana fermions.The spintronics arena is flourishing more than ever.While devices based on magnetoresistive phenomena have been in production for several years now, a plethora of new materials and concepts just entered the game, offering the potential to make a significant leap forward.This special issue of "Interfaces in Spintronics" in Advanced Materials Interfaces is a collection of reviews, perspectives, and original research papers, which focus on the intimate connection between interfaces' properties and their target application in spintronic devices.The content ranges from the development of novel materials (two-dimensional ferromagnets, topological insulators, Weyl semimetals, Heusler alloys and emerging ferri-and antiferromagnetic compounds) to their inclusion in mature spintronic devices such as magnetic tunnel junctions.A number of papers also address the manipulation of magnetic properties of materials through molecules, magneto-ionic or magneto-electric effects, and by excitation with light.The comprehensive characterization of interfaces with a wide range of analytical tools (such as spin-orbit torque, terahertz spectroscopy, ferromagnetic resonance and Mössbauer spectroscopy) is also the subject of several contributions.Thanks to a strong interdisciplinarity of the collected manuscripts, this special issue could serve as a basis to establish fruitful connections among research groups from all over the world.More than ever, interfaces will keep playing a key role in driving the functionalities of future spintronic devices, to the point in which the interface will be the device.Sharing complementary expertise will be fundamental to address present and future open questions in the field.