What happens to power lost in a feed line?

When radio frequency (RF) energy travels through a feed line like coaxial cable, some of the power is naturally lost due to the resistance of the metallic conductors and the dielectric losses in the insulation. According to the laws of physics, energy cannot be destroyed, only changed in form. In this case, the electrical energy lost to resistance is dissipated as heat into the surrounding environment. Distractors like "radiated as harmonics" or "distorts the signal" are incorrect because feed line loss simply attenuates (weakens) the signal rather than changing its frequency content. It also does not increase SWR; in fact, high line loss can deceptively make SWR read lower at the transmitter end because the reflected power is also attenuated on its way back.