The developments in different communication technologies paved way to the large-scale success of Telecommunications. A branch of Electronics, Signal Processing, defines the different type of signals and the their efficiency in communication. Two basic different types of signals are: Analog and Digital Signals. Analog signals carry data in the raw form, where as digital signals carry precise dimensions of data due to which digital communications came to be known as the most efficient way of communication. When analog signals are carried from one destination to another, due to their abstract nature, it is difficult to eliminate noise from the raw signal. When the same signal is compared to a processed digital signal, a clear distinction in the amount of reduced noise can be seen. This processing of the raw signal to get a desired output is called Signal Modulation. The process of delivering meaningful information by encoding digital signals in analog signals, to facilitate uninterrupted flow of signal is called keying. There are different keying techniques: phase-shift keying, frequecy-shift keying, line-coding and amplitude-shift keying. Based on the data that is streamed over the analog channel, there are: digital modulation, analog modulation, digital baseband modulation and pulse modulation.