It allows you to write programs using the C# language and the .NET 2.0 Compact Framework (.NET2CF). The program is parsed and executed at runtime (there is no compilation or link required).

Important note:
No .NET SDK IS REQUIRED: Unlike other tools which do "C# Scripting" by wrapping CSC.EXE, C# IDE Mobile doesn't require you to have the .NET SDK (which includes the compilers). It only requires having the .NET 2.0 (Compact or not) Framework Redistributable (i.e. the runtime .NET). It isn't a wrapper around the Microsoft CSC.EXE compiler.

The goal is mainly to develop code while away from your desktop and be able to test it. Then you can compile into native PPC applications using Microsoft's compilers (with Visual Studio for example).

Here are just some examples of what is possible on your Pocket PC thanks to this:
- Creating applications with graphical user interfaces.
- Creating methods and classes (to better organise your program into smaller functions).
- Using all of the.NET Compact Framework classes.
- Doing file manipulation (.NET as many nice static functions for this).
- Running processes.
- Using .NET2 generics (to create lists, tables, arrays, ...).
- Using C# control structures (loops, conditional, ...).
- ...

Basically, you can write C# code and execute it on your Pocket PC (then you can compile it later on your desktop to get a native .NET program).

Update Description:
v12.0:
- Added support for multi threading.
- Added support for do/while loop.
- Added support long type.
- Fixed bug with RelationalOp.
- Improved error location (line number).
- Enabled Paint and MouseMove events.

v11.0:
- Included new Windows Forms Designer (yes, you now have a Windows Form designer usable directly on the PPC) developed by Jean (http://pagesperso-orange.fr/asnora/Control%20Editor/Control%20Editor.htm).
- Added support for compiled User Plugins (DLL instead of css).
- Corrected issue with "Format document".
- Added replacement File Dialog for smartphones on which the default .NET2CF FileDialog DLL is missing (this seems to be the case sometimes).
- Added support for user DLLs: You can now place your own CF DLLs (generated with Visual Studio for example) in the "UserDLLs" folder and call your functions within them (you can create your API for example in a native CF DLL and call these functions from your C# IDE Mobile code).

v10.0:
- Added "Menu/Edit/Advanced/Format document" to automatically format the C# code in a compact and indented text.
- Added new useful entries in the "Menu/Insert code" menu.
- Corrected problem with indexers on collections when polymorphism is involved.
- Improved support for CSS plugins (when plugin contains multiple windows).
- Corrected problem with some Events.
- Fixed problem with error localisation.
- Added support for multi dimensional arrays (as in "int[,] test=new int[5,4];").

v9.0:
- Fixed issue with declaring size of initialised array (like in "new int[2]{4,6};").
- It is no longer necessary to fully qualify locally declared class names (before you needed to write like "TestNS.MyClass" even if you were already in "TestNS").
- Fixed bug with logical operators on enum types (for example on button.Anchor = AnchorStyles.Bottom | AnchorStyles.Right).
- Manual casting is now supported. Usually, C# IDE Mobile auto casts when possible, but for example, in "int test = (int)AnchorStyles.Bottom" manual cast is necessary. Also, this avoids removing casts required in VS.
- Fixed bug with multiple "if"/"else if"/"else" structures.
- "static" keyword now works for arrays and generics, also fixed a problem with indexed assignments.
- Added support for nested classes (like System.Windows.Forms.ListView+SelectedIndexCollection).
- Added support for double type.
- Improved comment and string parsing (to avoid "//" making a mess in strings).

v8.0:
- The main limitation of previous versions is now history: It is now possible to create new classes and instantiate them (these can inherit from .NET types, for example Forms created from VS designer now execute with no changes).
- Added "Insert code" menu to easily insert recurring blocks of code (functions, classes, loops, …).
- Small bug fix on escape character support.
- Improved expression end detection (this caused some problems in "complicated" expressions, which could need cutting down in some cases).
- Improved error location indication (in some cases the outer function was indicated instead of the line in the function).

v7.0:
- Added "light" support for user plugins (allowing users to create plugins to facilitate/automate development in conjunction of copy/paste)..
- Resolved major (but rare) issue with scope management..
- Floats are now parsed culture independent..
- Reworked undo/cut/copy/paste to use WM clipboard (Paste no longer moves the scroll/caret and copy/paste works with other apps)..
- Fixed negative number declarations (like "int i=-1;", "if(i<-5)", …)..
- Fixed support for escape characters ('\n', '\r', '\r\r', '\t')..
- Fixed support for char types and array initialisation.

v6.0:
- Added support for undo/cut/copy/paste in the editor windows.
- Types and functions can now be copied from the "MS.NET2CF Index" window to the editor.
- The "MS.NET2CF Index" window is now persistent between calls (avoids reselecting the Type each time).
- On errors it is now possible to choose to select the error or not (leave the cursor where it was, avoids getting lost).