of the black-hole geometry to a fuzzball. The defining characteristic of the fuzzball is that it has structure at the horizon scale. This should be contrasted with the conventional picture of the black-hole interior as a largely-featureless region of space. For a large enough black hole, tidal effects are very small at the black-hole horizon and remain small in the interior until one approaches the black-hole singularity. Therefore, in the conventional picture, an observer who crosses the horizon may not even realize that they have done so until they start approaching the singularity. In contrast, the fuzzball proposal suggests that the black hole horizon is not empty. Consequently, it is also not information free since the details of the structure at the surface of the horizon preserve information about the initial state of the black hole. This structure also affects the outgoing Hawking radiation and thereby allows information to escape from the fuzzball. The fuzzball proposal is supported by the existence of a large number of gravitational solutions called microstate geometries. The firewall proposal can be thought of as a variant of the fuzzball proposal except that it posits that the black-hole interior is replaced with a firewall rather than a fuzzball. Operationally, the difference between the fuzzball and the firewall proposals has to do with whether an observer crossing the horizon of the black hole encounters high-energy matter, suggested by the firewall proposal, or merely low-energy structure, suggested by the fuzzball proposal. The firewall proposal also originated with an exploration of Mathur's argument that small corrections are insufficient to resolve the information paradox. The fuzzball and firewall proposals have been questioned for lacking an appropriate mechanism that can generate structure at the horizon scale. Strong-quantum-effects resolution to the paradox In the final stages of black-hole evaporation, quantum effects become important and cannot be ignored. The precise understanding of this phase of black-hole evaporation requires a complete theory of quantum gravity. Within, what might be termed, the loop-quantum-gravity approach to black holes, it is believed that understanding this phase of evaporation is crucial to resolving the information paradox. This perspective holds that Hawking's computation is reliable until the final stages of black-hole evaporation when information suddenly escapes. An alternative possibility along the same lines is that black-hole evaporation might simply stop when the black hole becomes Planck-sized. Such scenarios are called "remnant scenarios". An appealing aspect of this perspective is