The book addresses capillary phenomena, which at the macro-scale are a part of our everyday experience. This includes clustering of cereals in a bowl of milk or locomotion of insects on a water surface. At the micro-scale, when gravity can be neglected, capillary forces are even more pronounced as they determine the shape of free liquid interfaces and therefore become a major factor governing the behavior of microscopic objects trapped at these interfaces. The book describes the effective interactions between colloidal particles deforming the surface of a micron-sized droplet deposited on a solid substrate and the possible equilibrium configurations of the particles on the droplet. The issue is of big relevance for experimental techniques, frequently employed in science and industry, which use sessile droplets for transferring the self-assembled colloidal structures onto the substrates.