What is '1 in Collection type Name

I was wondering what '1 means in Collection type name? For example: List'1, IList'1 Does anybody know what that is?

How many types of collection in c#?

Collections in C# are classified into two types - Generic collections and non-generic collections.

What is type name in C#?

" typename " is a keyword in the C++ programming language used when writing templates. It is used for specifying that a dependent name in a template definition or declaration is a type.

The backtick indicates:

The name of a generic type ends with a backtick (`) followed by digits representing the number of generic type arguments. The purpose of this name mangling is to allow compilers to support generic types with the same name but with different numbers of type parameters, occurring in the same scope.

http://msdn.microsoft.com/en-us/library/w3f99sx1(v=vs.110).aspx