Quantum circuit
The standard way of describing a quantum program: qubits as horizontal lines, gates as boxes, measurement at the far right.
The notation reads left to right in time. Each line is a qubit, each symbol an operation, and vertical bars connect several qubits in two-qubit gates. The format is established enough to serve as the field's common language regardless of which framework you code in.
Two measures matter. Width is the number of qubits; depth is how many layers of gates run in sequence. Depth is the critical one on today's hardware, since each layer takes time and time is bounded by decoherence. Recompiling a circuit into fewer layers is therefore a central optimisation.