For questions related to Noisy Intermediate Scale Quantum (NISQ) computing. NISQ computers cannot be classically simulated in a reasonable time but are not advanced enough to also be error corrected.
Noisy Intermediate Scale Quantum (NISQ) computers have enough qubits to see non-classically-simulable behavior, but not enough for error correction. NISQ algorithms often revolve around sampling very short circuits many times and using classical feedback to choose which circuit to sample next. The cost bottlenecks for NISQ computation are things that introduce noise into the results (e.g. circuit depth and two-qubit gates).
See John Preskill's 2018 paper "Quantum Computing in the NISQ era and beyond".