What is the function of taps in a digital signal processing filter?

In digital signal processing (DSP), particularly within Finite Impulse Response (FIR) filters, "taps" refer to points where the signal is extracted after passing through a series of delay elements. Their primary function is to provide incremental signal delays for the mathematical filter algorithms. As a digitized signal flows through the filter, each tap captures the signal at a slightly different moment in time. The DSP software multiplies the signal value at each tap by a specific constant (a coefficient) and adds them all together. This combination of delayed and weighted signals is what shapes the filter's frequency response. The term "tap" has nothing to do with debugging or reducing signal levels; it is a mathematical concept analogous to tapping into a physical delay line.