Filtering of data in signal processing

Filtering is a class of signal processing, the defining feature of filters being the complete or partial suppression of some aspect of the signal. Most often, this means removing some frequencies or frequency bands.

1. What are the three types of filtering?
2. How many types of signal processing filters are there?

What are the three types of filtering?

Filters can be active or passive, and the four main types of filters are low-pass, high-pass, band-pass, and notch/band-reject (though there are also all-pass filters).

How many types of signal processing filters are there?

There are two types of filters in the digital realm: Finite Impulse Response (FIR) filters and Infinite Impulse Response (IIR) filters.