What is a mutex and what is a monitor?

I asked myself to understand what is what. Since different sources use these terms differently. And it often even happens that in one article something, for example, a piece of code, is called a monitor, in another it is called a mutex (and it happens vice versa - an object associated with the data and responding to thread synchronization is called either a mutex or a monitor ). So I want to figure out what is what. (I can, of course, give many quotes from these sources where these terms are used, but I think this will be redundant.)