**Acknowledgements**

I have no words to express my sincere and deep gratitude to my Editor from IntechOpen for a full chapter Review consisting of meticulous and painstaking criticisms, and insightful suggestions which enabled me to bring the paper to its present somewhat decent shape. I also cannot refrain myself from mentioning the name, Mrs. Chaitali Gupta, my wife, whose care and constant encouragement to complete the paper made it possible for me to work hard and finish it during the time of pandemic and devastations by an extremely severe cyclonic storm arising from the Arabian sea, called Tauktae, and when I was not keeping well. I must convey my sincere appreciation to Ms. Madhavi Rao for going out of her way in helping me to bringing the paper in its present form.
