This book is a condensed explanation of frequency mixers used in the electronic communication industry. Chapter 1 starts by defining the mixer and introduces concepts such as the harmonic intermodulation table, input and output intercept points, and other definitions. Chapter 2 introduces more advanced concepts such as BPSK and QPSK decoding and the Weaver method of single sideband generation and decoding. Chapter 3 is a full derivation of equations that define the gilbert cell, considering that most integrated circuits that implement mixers do so by using a gilbert cell. Chapter 4 is an overview of different types of mixers, starting with the Pentagrid mixer, includes different types of mixers used in analog and digital phase locked loop circuits, and ends in a little know technique using analog-to-digital conversion as a mixer for down converting. Chapter 5 shows how to use mixers for analog computation functions such as multiplication, division, squaring, and square root, including powers and roots that are non-integral. Chapter 6 gives application examples with working schematic slices for each example. Chapter 7 provides complete schematic examples of different types of mixers used in radio receivers.