The term signal processing refers to the science of analyzing time-varying physical processes. In general, a signal can be defined as a function that conveys information, generally about the state or behaviour of a physical system. Signals are represented mathematically as functions of one or more independent variables. As real world signal processing is concerned the independent variable is generally time.

The independent variable in the mathematical representation of a signal may be either continuous or discrete. Continuous-time signals are defined along a continuum of times and thus are represented by a continuous independent variable. Continuous-time signals are often referred to as analog signals. In other words, analog signals are those waveforms that are continuous in time and can take on a continuous range of amplitude values. On the contrary, discrete-time signals are defined at discrete times and thus the independent variable has discrete values. A discrete-time signal is not represented by a continuous waveform but, instead, a sequence of values. Besides the independent variables being either continuous or discrete, the signal amplitude may be either continuous or discrete. Digital signals are those for which both time and amplitude are discrete. In addition to quantizing time, a digital signal quantizes the signal amplitude.

Signal processing systems may be classified along the same lines as signals. That is continuous-time systems are systems for which both the input and the output are continuous-time signals, and discrete-time systems are those for which both the input and the output are discrete-time signals. Similarly, a digital system is one for which both the input and the output are digital signals. Digital signal processing (DSP for short) deals with the transformation of signals that are discrete in both amplitude and time.

Digital signal processing is the most dynamically growing field of the semiconductor industry. DSP algorithms and processors are having an impact similar to the effect the microprocessor had on computing. DSP has already reshaped or will reshape the complete electronics industry. DSP technology makes a variety of signal processing algorithms, thus a variety of new applications possible, which cannot be implemented with analog technology. The inherent processing power and the applied system-on-a-chip philosophy of the DSP processors makes the possible fields of application practically unlimited. Besides the CISC (Complex Instruction Set Computer) and RISC (Reduced Instruction Set Computer) architecture, DSP has became the third microprocessor architectural paradigm and, at the same time, the greatest business of the semiconductor industry.