Quantum computing uses quantum bits that can be both 0 and 1 simultaneously, allowing for exponentially faster computation than classical computers. While early quantum computers were prone to errors, major tech companies are working to build stable, larger quantum computers - a 30 qubit computer would have commercial applications, and 50 qubits would demonstrate "quantum supremacy" over classical computers. Potential uses of quantum computing include solving complex optimization problems, machine learning algorithms, and pharmaceutical research.