M2M devices are ubiquitous, and there is a growing tendency to connect such devices to mobile networks. Network operators are investigating new solutions to lower their costs and to address usability issues. Embedded SIM cards with remote provisioning capability are one of the most promising solutions. GSMA, the leading consortium on mobile network standards, has proposed a specification for such an embedded SIM card, called eUICC. The specification describes eUICC architecture and a remote provisioning mechanism. Embodiments of this specification have the potential to disrupt the telecommunications market: eUICCs will be shipped to device manufacturers and then remotely provisioned with a subscription, whereas (currently) SIMs must be provisioned prior to shipping. In this article, we present a comprehensive overview of GSMA's specification and its motivation. In particular, we describe the technology and the protocols involved in remote provisioning.