Every module will have a `module` variable available to it. `module` defaults to { id: ... exports: {} parent:... filename:

Every module will have a `module` variable available to it. `module` defaults to { id: ... exports: {} parent:... filename:... loaded:... exited:... children:... paths:... } Whatever module.exports is at the end of the module is passed to the require statement. Every file essentially has two lines at the top. this = module.exports; var exports = module.exports; The first helps lazy developers by allowing exporting without explicitly saying so. Because of this, the following alone is a valid module that exports {foo:'bar'} foo = 'bar'; // can also be written as this.foo = 'bar'; And the second matches the CommonJS standard. So the following CommonJS module will work: exports.foo = 'bar'; If you assign module.exports at any time after using `this` or `exports`, module.exports will point to the new object, and anything on the original module.exports object wont be passed to the `require` call.