Basically the objects which are highly depend upon each other are known as tightly coupled. Changing one object in a tightly coupled application often requires changes to a number of other objects
Loose coupling is a design goal that seeks to reduce the inter-dependencies between components of a system with the goal of reducing the risk that changes in one component will require changes in any other component.
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Editor, DotNetSpider MVM
Microsoft MVP 2014 [ASP.NET/IIS]