In physics and engineering the quality factor or Q factor is a dimensionless parameter that describes how under-damped an oscillator or resonator is, and characterises a resonators bandwidth relative to its center frequency. Higher Q indicates a lower rate of energy loss relative to the stored energy of the resonator; the oscillations die out more slowly. A pendulum suspended from a high-quality bearing, oscillating in air, has a high Q, while a pendulum immersed in oil has a low one. Resonators with high quality factors have low damping so that they ring longer.
A Quick Response or “QR” Code is a type of two-dimensional barcode. Unlike the conventional barcodes found on items such as supermarket groceries, a QR code can be read quickly by devices such as cameras and the codes have therefore become popular when designed to be read by smartphones. Usage could be the encoding of a web URL or additional information stored in a code on a printed advertisement.
Only scan QR codes you trust. Scammers can make QR codes which link to fake websites that trick you into giving away personal details.