Frequency Shift Keying (FSK) is a digital modulation technique used to transmit data by varying the frequency of a carrier wave. In FSK, different frequencies represent different binary values, typically 0s and 1s. This method is commonly used in applications like modems and radio communications due to its robustness against noise and interference. There are two main types of FSK: binary FSK (BFSK), which uses two frequencies, and multi-level FSK, which can use more than two frequencies for higher data rates. FSK is widely utilized in wireless communication systems and data transmission protocols, making it an essential technique in modern telecommunications.