Surface coating applying to critical parts enhances the durability, resistance, wear and endurance of tools, materials and machine components that require desired surface properties like corrosion, erosion and wear resistance. To improve surface properties such as corrosion, adhesion, erosion, and wear functional resistance coating are employed. Currently, plenty of coating methods are applied to achieve the desired functional or decorative properties. The thermal spray coating process is one of the cost-effective and attractive methods to preserve the new machine components from mechanical wear, corrosion, and erosion problems. This paper briefly explains different spray processes, basic principles, advantages, and applications in a simple way.