Nowadays, expanded cereal grains are greatly gaining popularity because they are easy to digest, light, crispy, and the most interesting that these products are ready for eating. Popping and puffing are simple and low-cost processes used for producing crispy-expanded products with an open porous structure, such as popcorn, puffed rice, and popped/puffed wheat. These expanded products can be produced by many different techniques, like hot sand bed, hot oil, hot air, gun and microwave puffing, and instant controlled pressure drop. Recently, infrared puffing has been adopted to produce these products. The mechanism of these techniques is based on the exposure of grain to high temperature for a short time, resulting in a phase transition from an amorphous to a rubbery state that ensures creating a sufficient superheated steam pressure within the grain matrix. The release of this pressure afterward causes the grain structure to expand. This chapter provides a review of different popping and puffing methods for cereal grains and covers the various quality attributes of popped and puffed cereal snacks as well as the factors affecting this quality.