Hi Kirti,

Instead of asling people to help you, an intelligent person like you should first try and find out yourself and then ask probing questions based on your studies. For example, you can go to Attrition and retention in CS

http://www.manpower.ie/company_infor..._Workplace.pdf

Customer retention or attrition – the decision is yours - 27 May 2008

I hope you find these useful
Wish you all the best.