Thermal noise, also known as Johnson-Nyquist noise, is the random electrical noise generated by the thermal agitation of charge carriers, such as electrons, in a conductor. This phenomenon occurs in all conductive materials and is directly related to temperature; as the temperature increases, the level of thermal noise also rises. This type of noise is significant in electronic devices, particularly in resistors and amplifiers, where it can affect signal quality. Understanding thermal noise is essential for designing sensitive electronic circuits and improving the performance of communication systems.