RMS stands for root mean square and refers to the continuous power handling capacity of a speaker or amplifier. It is a measurement of the average output of a device over time without causing any damage. RMS values are usually lower than peak power ratings, which refer to the maximum power level that a speaker can handle in short bursts. For example, a speaker with a 30W RMS rating but a peak rating of 60W means that the speaker can comfortably run with 30 watts of continuous power, with occasional bursts of up to 60W. Both RMS and peak power ratings are important when comparing speakers and amplifiers, and it is essential to understand the difference between the two when building a high-performance sound system.