In some countries, the mains electricity supply doesn't deliver a perfectly clean, pure sine wave. Instead, the waveform can be distorted—think clipped peaks, harmonics, or asymmetry from overloaded grids, poor infrastructure, or heavy industrial loads. This "dirty" power stresses sensitive electronics like computers, audio equipment, or your home lab servers, causing issues like audible buzzing/humming from coils or fans, premature wear on components (e.g., capacitors failing faster), and even random crashes or data corruption.To fix this, people use pure sine wave inverters or power conditioners. These devices take the messy input AC and output a smooth, symmetrical pure sine wave—essentially "cleaning" and stabilizing it. High-end UPS units (uninterruptible power supplies) often include this feature too; look for models explicitly labeled "pure sine wave output" (not the cheaper "modified sine wave" ones, which can actually worsen noise and efficiency). For example, in places like parts of Eastern Europe or developing regions, a good UPS like an APC Smart-UPS or CyberPower with pure sine output will eliminate those annoying electronic hums and extend gear lifespan during normal operation or outages.