what is DLL Hell and how it is solved in .NET?

Dll Hell refers to a set of problems caused when multiple 
applications attempt to share a common component like a 
dynamic link library (DLL). The reason for this issue was 
that the version information about the different components 
of an application was not recorded by the system. 

.Net Framework provides operating systems with a Global 
Assembly Cache. This Cache is a repository for all the .Net 
components that are shared globally on a particular 
machine. When a .Net component is installed onto the 
machine, the Global Assembly Cache looks at its version, 
its public key, and its language information and creates a 
strong name for the component. The component is then 
registered in the repository and indexed by its strong 
name, so there is no confusion between different versions 
of the same component, or DLL.