Prototyping is an important aspect in the design process, it is a process through which design teams showcase and implement all the work that has been done in the previous stages of the design process and what the product should look like and how the product will function.
Rapid Prototyping is a method of quickly creating mockups of your tool, product, system or a website and showing it to the User before the product is actually implemented and developed.
Usability lab test is a qualitative research method which is an integral and important part of the user-centered design process and its function is to observe and measure how effective a product is.