What is a Class 8 steel equivalent to?

I'm curious, could you explain to me what a Class 8 steel equivalent is? I've heard of steel being categorized by classes, but I'm not quite sure what that means or how it relates to other types of steel. Is there a specific property or characteristic that defines a Class 8 steel? And if so, how does it compare to other grades or classes of steel? Additionally, are there any common applications or industries that typically use Class 8 steel?