Microcirculation is a part of the vascular system comprising the most minor blood and lymphatic vessels. It is present in the majority of organs. The microcirculation unit is built up by a series of sequential segments, displaying their own characteristic structure and physiological functions. The vessels on the arterial side of microcirculation are named arterioles, while venules reside on the venous side. Capillary beds are located between these two structures. Lymphatic micro-vessels are present in the surrounding tissue and consist of blind-ended sacs of lymphatic capillaries, also called terminal lymphatics. The microcirculatory architecture is site-specific and highly adapted to local functions in each tissue and organ. Interstitial fluid, leaving the capillary vessels and deriving from the intercellular space, enters the initial blind-ended lymphatic sacs. The glycocalyx is a crucial component of the vascular wall that greatly influences microvascular permeability. Microcirculation plays a significant role in living organisms and contributes to the continuous renewal and maintenance of organ homeostasis. The main functions of microcirculation include the delivery of oxygen, water, nutrients and signalling proteins to cells of all organs, the removal of carbon dioxide and cell waste metabolic products from tissues, maintenance of interstitial fluid balance, lipid absorption and several immune properties. Microcirculation is a very complex and active unit. Regulation of blood flow, as well as filtration and reabsorption processes within the microcirculation, is controlled by many factors operating simultaneously and deriving from upstream and downstream vascular segments and the closest underlying interstitium. Microcirculatory dysfunction occurs in many, not only cardiovascular, diseases. Mechanisms leading to insufficient blood flow through microcirculation include decreased inflow or outflow to or from the microcirculatory vascular bed, impaired regulation of vascular contraction/relaxation and increased/decreased vascular permeability.