Radio sources of solar origin are the dominant feature of radio emissions at low frequencies. Solar radio sources are sporadic and very frequent during the maximum phase of the solar cycle; they may be very intense (more than 40 dB above the background) and they can be localized almost anywhere in the interplanetary medium. They represent a unique means to detect perturbations originating from the solar activity and to track their progression through the interplanetary medium and particularly into the Earth’s environment.