Frequencies refer to the number of times a particular event occurs within a specific time period. In physics, it often relates to waves, such as sound or light, where frequency measures how many wave cycles pass a point in one second. It is typically expressed in hertz (Hz), with one hertz equating to one cycle per second. In everyday life, frequencies can be observed in various contexts, such as music, where different notes correspond to different frequencies. For example, the note A4 has a frequency of 440 Hz. Understanding frequencies helps in fields like telecommunications, where signals are transmitted at specific frequencies to avoid interference.