Networks are all around us: there are river networks, streets, cracks patterns, veins of leaves, ants nests, social networks. But they are also within us, for instance our blood vessels. Appart of the social networks, the particularity of these networks is to be drawn in physical space. Some are branched like trees, rivers networks or lightning, but many, especially in living matter, form loops. These loops are very useful in case of a disturbance, for instance when a blood vessel blocks or a street jamms, the flow can turn around and keep circulating. What is surprising is that these networks are not well described. We start to know pretty well how to describe trees, or social networks, but we are missing a lot of information by not using the presence of these loops and their position in space. There is also no understanding of how they grow and appear. This is why this meeting happens: to bring together experts of these up to now separated subjects, to form a new community and bring discoveries around this common object.