Left atrial (LA) strain is gaining more and more relevance in medical literature, with many applications in different clinical setting. The term “strain”, meaning deformation, is applied to the contraction phase of the left ventricle (LV), due to its myocardial shortening along the longitudinal axis, to the LA relaxation phase, correlated to its distensibility and elastic compliance in receiving blood from the pulmonary veins, and even to LA contraction consequent to the electric activation of LA myocardium. This manuscript describes main anatomical and physiological characteristic of the left atrium and discusses the use of the term strain from terminological and conceptual points of view.