this is what i found by doing a google search.....
The module msctf.dll file extends the functionalities drawn by the Microsoft Text Services. Among its basic functions is the implementation of advanced text input and text processing.
The functionality offered by the msctf.dll file allows for bidirectional communication between application and text services. As part of the Microsoft Windows Text Services framework, the msctf.dll file proves essential in running a simple and scalable framework for text input and natural language technologies. This module provides multilingual support and can deliver various text services. This includes keyboard processors, handwriting recognition and even speech recognition.
The msctf.dll file is used to initialize the Language Bar, which is the core user interface for the text services. Executing the language bar function in the text services allows for UI elements to be added to the toolbar and allows the user to make use of these elements in an application. The Language Bar including controls for keyboard input along with recognition of handwriting and speech trigger several controls. When the msctf.dll file is called through the language bar, the user is also allowed to switch between installed languages even when a non-TSF-enabled application has focus.
The features of text services can be extended to text applications by Independent software vendors (ISVs). By calling on the msctf.dll file into the application, ISVs will be able to write their own text processing feature for TSF. It is also possible to store metadata with a document, a piece of text, or an object within the document through the TSF. Text services using the functionalities of the msctf.dll file can convert text accurately and completely. This is made possible by the input architecture in the msctf.dll module, which allows buffered and accumulating text to change dynamically. This enhanced function results in more efficient keyboard input and text servicing.
The msctf.dll file supports all text service devices operated on Windows. It can provide text services for multiple input devices including keyboard, electronic pen or stylus and microphone.