Bolts come in various grades, each denoting its material properties and strength. The most common grades include Grade 2, a standard low-carbon steel bolt for general use with lower tensile strength; Grade 5, medium carbon steel with higher tensile strength, often used in automotive applications; Grade 8, high-strength alloy steel bolt, ideal for demanding structural and machinery purposes. Additionally, there are stainless steel grades like A2 and A4 known for their corrosion resistance. The grade of a bolt is crucial in determining its suitability for specific applications, ensuring safety and reliability in various industries.