what is managed && unmanaged code?

As far as my knowledge the following statements will help you to differentiate between managed & the unmanaged code:

As the name unmanaged code implies the code is completely not in control which indirectly tells us that its a third party software. You are executing a third party software on ur machine and you dont know how it works but yet it works exhibiting its interface to the outside world.

managed code in other words are generated by ur machine - for example a simple c++ program compiled by a borland compiler will generate a file which can be run directly on the same machine. Here the compiler has generated the output(infact it created the origin) where by we can say that the output is managed code for the compiler.
If you wrap this code into an exchangable component(like a dll) and give it to someone else your code will be unmanaged code to the machine which uses your code.
Ex: - Internet Explorer is an example of unmanaged code bcoz it can run .aspx files written and compiler by the .net framework