This paper reviews the present understanding of defect formation and development in relation to process conditions in 4H-SiC crystal growth and epitaxy. The polytype uniformity during seeded sublimation growth of SiC boules has been discussed. Insight into different structural imperfections has been attempted. The role of the temperature distribution, as well as of the quality of seed/crystal interface in the occurrence of grown-in defects has been demonstrated. Micropipe termination by liquid-phase deposition along with defect evolution in subsequently grown layers due to rough interface has been addressed. Finally, a relation between extended morphological defects in thick (50-100 mum) 4H-SiC epitaxial layers and local stress in the material has been suggested. Optimised growth conditions to reduce the overall defect density have been proposed.