1. A method for analyzing a tennis session for game improvement using a portable device and a tennis analysis system, said method comprising: collecting information from said tennis session using said portable device attached to a racket used in a game for a plurality of strokes, said information includes at least one among acceleration of the racket, rate of rotation of the racket for x, y, and z axis, swing speed of said racket, time markers, and result markers; transferring said collected information from said portable device to said tennis analysis system using a communication interface; analyzing information relating to said plurality of strokes, where said analysis includes at least classifying said stroke, by said tennis analysis system; analyzing information relating to collections of strokes from said plurality of strokes to identify rallies, games, sets and matches played during the session, by said tennis analysis system; and generating a plurality of game statistics using information available from said analysis of plurality of strokes and said analysis relating to a collection of strokes from said plurality of strokes, by said tennis analysis system, wherein said portable device comprises of a processor, a sensor module including at least a gyroscope sensor and an accelerometer sensor, and a plurality of communication interfaces, and wherein said tennis analysis system comprises a tennis analysis engine; and wherein classifying said stroke comprises: identifying stroke peak of said stroke, identifying category of said stroke, wherein said category is one among a short swing stroke, and a long swing stroke, and identifying type of said stroke, wherein the type of said stroke is identified based on number of consecutive data points in stroke window of said stroke with reference to a pre-defined threshold number.