What is the Quantum Spectral Curve?

N=4 Super Yang-Mills (SYM) is a highly symmetric theory which, remarkably, appears to be solvable in the planar limit. In particular, the full non-perturbative spectrum is believed to be encapsulated in the integrability-based Quantum Spectral Curve (QSC). I will describe the QSC, its basic building blocks and it the process review what data the formalism is now able to provide. In the end I will turn to recent applications and briefly discuss attempts at understanding the spectrum of N=4 SYM at strong coupling and at non-integer spin.