What is nucleosynthesis? How is it related to the Big Bang?
Nucleo-synthesis is the process of creating atomic nuclei heavier than hydrogen.
Nucleo = Nuclei
Synthesis = joining, merging.
In the early days of the Universe there were only protons, neutrons and electrons. Nucleo-synthesis is required to make the heavier elements.
Soon after the Big Bang, the so called "Big Bang Nucleo-synthesis" took place which created helium and traces of lithium and beryllium.
In modern times nucleo-synthesis takes place in stars, supernovae and cosmic ray interactions.