The process whose specific outcome is the progression of the myoblast over time, from its formation to the mature structure. A myoblast is a mononucleate cell type that, by fusion with other myoblasts, gives rise to the myotubes that eventually develop into skeletal muscle fibers. [ GOC:mtg_muscle http://purl.obolibrary.org/obo/CL_0000056 GOC:dph ]