What makes quantum computers fundamentally different from regular computers?

The answer

Classical computers use bits that are either 0 or 1, while quantum computers use qubits that can exist in a 'superposition' of both states simultaneously. When qubits are entangled, measuring one instantly affects the other regardless of distance. This allows quantum computers to explore vast numbers of possibilities in parallel, making them exponentially faster for specific problems like cryptography, drug discovery, and optimization. However, qubits are extremely fragile - most must be cooled to near absolute zero (-273°C) to function.