• IEnumerable is an interface available in the System.Collection namespace
• Any collection that implements the IEnumerable implements the GetEnumerator method of the IEnumerable interface, making it iterable.
• The IEnumerable or the Generic IEnumerable must be used over in-memory objects.

• We can compile .NET Framework projects without using Visual Studio on the Command Line using csc.exe file.
• We can supply additional arguments to csc.exe, in-addition to the csproj file of the .NET project.
• In .NET Core, we use the dotnet build command on the command-line which can build the csproj without using Visual Studio.

• A JIT (Just-In-Time) compiler converts the MSIL (MS Intermediate Language) into native code on demand during the application runtime, when the application components are loaded and executed.
• The JIT compilation happens specific to the running CPU architecture, since the common language runtime supplies a JIT compiler for each supported CPU architecture.
• If the managed code calls platform-native APIs or runs platform-specific assemblies, the JITed code runs on only that particular system.

• A Tuple is a data structure which can hold data of multiple types in a single variable.
• Tuple was first introduced in .NET 4.0.
• A Tuple can generally represent a row in a database table, where each column can represent a different type.
• Individual values of "Items" inside a single tuple variable can be accessed by means of properties (Item1, Item2, ..)
• A tuple can hold a maximum of 8 Items in itself, where the individual Items can themselves be Tuples of different items.

var tuple = new Tuple<T1, T2, T3, ... , T7, T8>();

• GAC stands for Global Assembly Cache
• It is a place in the Windows directory where the assemblies (the DLL files) designated to be shared by the applications are stored for reuse.
• Any assembly or component which is desired to be shared across applications in a machine is registered on the Global Assembly Cache.
• To register an assembly into the Global Assembly Cache, we can do so by using the GACUtil.exe as below:

> gacutil -i [Path][Assembly Name].dll

Namespaces are used to group and organize classes which are somewhat related to each other. Any class created would reside under a namespace and is referenced using the namespace in other classes or modules.

namespace MyModule {
  class MyClass {
   // all things under class
  }
  class MyOtherClass {
   // all things under class
  }
}