Nucleosynthesis starts from the earliest time of the universe, a few seconds after the Big Bang when the first elements and nuclei were created. After the star formation new processes began in their interior, starting a new phase of the nucleosynthesis. By studying evolution of stars and nuclear reactions which take place in their surroundings, we can explain why element abundances are distributed in accordance to observations, why are some elements more abundant than the others. Supernovas are especially interesting site for the synthesis of elements heavier than iron, but other astrophysical scenarios have also been discovered where such elements are created in some processes. Theory which describes how the elements heavier than iron are produced is based on four key processes: s-process, r-process (neutron capture), p-process and rp-process (proton capture). Our understanding of those processes is still evolving and there are still many open questions. The primary goal of this thesis is to explore and explain the ways how and places where the elements heavier than iron are synthesized, and to explain the structure of observed element abundances.