Basic Code Completion completes the name of classes, methods, variables or any other symbols that are available within the current visibility scope. It also completes C# keywords available in the scope.
You can choose to use the IntelliSense of VisualStudio.NET for Basic Code Completion. Please see IntelliSense Options.
To invoke Basic Code Completion:
The following examples illustrate this code completion for various C# code elements.
For variables and methods:

For members of an object instance:

For a currently-visible type name:

For C# keywords:

Commonly used names for fields and variables are suggested depending on their type:

The completion works even when you want a field or a variable to have a specific prefix:

Note ReSharper can automatically suggest prefixes according to your coding guidelines if preferred prefixes are specified in the appropriate Options tab.
Smart Code Completion | Type Name Code Completion | Advanced Editing Features | IntelliSense Options