what is mean by loose coupling and tight cohesion

[QUOTE=noman_mazher;19901]what is mean by loose coupling and tight cohesion[/QUOTE]

loose coupling" means that objects should only have as many dependencies as is needed to do their job

Cohesion is a measure of how closely the parts of a module or class are related. Ultimately, a class should perform a single task and all of the code in the class should support that task. This is known as high or strong cohesion. When a class begins to assume to many responsibilities or has code that is unrelated to the task, the class begins to exhibit low or weak cohesion.