This lecture explores network and network simulation in in silico neuroscience, focusing on simulating the time dimension, spontaneous and evoked network activity, in-vitro and in-vivo simulations, sensitivity analysis, and validation of network models. It covers the challenges, approaches, and applications of simulating brain microcircuits, including morphological and electrical diversity of neurons, synaptic diversity, and reconstructing microcircuit connectivity. The lecture emphasizes the importance of setting up simulations, conducting sensitivity analysis, and replicating experiments to validate and improve network models.