In many domains, such as robotics and power grids, where agents must coordinate their behaviors with limited information, communication constraints, and dynamic interconnections, synchronization in multi-agent systems is a crucial difficulty. This thesis investigates the synchronization issue in networks of nonlinear agents connected by dynamic links, emphasizing observer-based control schemes in particular. High-gain observers are used in these kinds of control laws to estimate the agent states and create feedback control laws that guarantee consensus. Simulations are conducted to validate the proposed approaches and show that they are effective in attaining synchronization even when there are disturbances and nonlinearities.