What is Signal-to-Noise Ratio (SNR) and why is it important?

Signal-to-Noise Ratio (SNR) is the ratio of signal power to noise power, typically expressed in decibels: SNR(dB) = 10*log10(Ps/Pn). Higher SNR indicates cleaner signal with less noise interference. SNR directly affects communication quality and achievable data rates (Shannon capacity). It determines bit error rate in digital systems. SNR is affected by transmit power, distance, interference, and receiver noise figure. System design aims to maintain adequate SNR throughout the communication link.