The liquid–liquid phase separation of binary fluids, induced by a temperature quench, can be arrested by colloidal particles trapped at the interface. The arrested structure, a novel soft solid known as a bicontinuous interfacially jammed emulsion gel (bijel), was first predicted by computer simulations and subsequently realized in the lab. Initially the mechanical properties are controlled by the interfacial tension between the two fluid domains (e.g. a deeper quench yields a stronger bijel) and the volume fraction of particles. Reversing the temperature quench results in the two fluids becoming miscible again. Whether or not this leaves a colloidal gel in place which is stable without a liquid–liquid interface (a ‘monogel’) depends on the age of the gel and the choice of liquids. In this chapter we describe the current state of bijel research using experimental, theoretical and computational approaches. We discuss possible areas of application and, finally, we contrast the physical route with which the bijel is prepared with a related material that is prepared via direct particle–particle interactions.