1. A method for online handwritten sub-word unit recognition on a communication means, using an application stored in a memory of a communication means; wherein the said method comprises the processor implemented steps of: a. providing an online handwritten text input using an input means through an user interface to the said communication means; b. sending the said online handwritten text input to spatio-temporal analysis module of the application; wherein the said spatio-temporal analysis module further comprises of a recognition engine for recognizing primitive strokes prior to sub-word units; c. subjecting the text input of step b) to stroke extraction and separation module of the application to extract and separate the strokes by comparing the said strokes to a primitive stroke database; d. subjecting the data of strokes obtained from step c) to the pre-processing module to pre-process the said extracted, separated and identified individual strokes by: i. reducing or removing the noise created due to the slow movement of the said input means using a noise removal module of the said pre-processing module to obtain noise free smooth data, and ii. optionally normalizing the size of the online handwritten text data by using the size normalization module of the pre-processing module; e. subjecting the pre-processed primitive stroke data of step d) to feature extraction module for modeling and representing the online handwritten text input; wherein the feature extraction module further comprises of: i. critical point identification module pertaining algorithms for identifying the critical points in the pre-processed smoothed data, and ii. fuzzy directional features for representing the strokes in the pre-processed smoothed data; f. subjecting the feature extracted data of step e) to stroke level recognition module for recognizing the primitive strokes, and further concatenating the said primitive strokes to form a sequence of strokes to further form a sub-word unit; wherein the stroke level recognition module further analyzes for any errors in the recognition of strokes using an evaluation and error analysis module; g. in case of any error, the evaluation and error analysis module helps in improving the stroke recognition; h. subjecting the sequence of recognized strokes of step f) for sub-word unit formation and sub-word unit recognition using the sub-word unit level recognition module; wherein the sub-word units are formed on the basis of the sub-word unit boundary information obtained from the sub-word unit boundary segmentation module and the defined rules for sub-word unit formation of the said sub-word unit level recognition module; wherein the sub-word unit recognition module further analyzes for any error in the recognition; i. In case of any error, the sub-word unit recognition results are backtracked through the error analysis module and modified based on the failure of the sub-word unit formation namely to put together a sequence strokes to form a sub-word unit.