How does multithresh and imquantize works

Can anyone explain about multithresh and imquantize? I've read the documentation regarding it but I don't really understand how does it works and how do they relate to each other.

If i have a thresh = multithresh(A,4) Does it means that it returns 4 threshold values from the image? How does the system decides which values to return? And we have imquantize(A,thresh). What would happen?