<br/>The biggest ever exercise in the history of mankind; "Census-2011" will be launched tomorrow covering over 1.2 billion residents of the country across all states and union territories. The mammoth operation will be formally launched by the President, Mrs. Pratibha Devisingh Patil at 10 am tomorrow. <br/><br/>Home Secretary GK Pillai told media persons that the whole exercise will be conducted in two phases. The first phase from April to September this year will involve house listing and housing census, the second phase of operation will involve population enumeration which will be carried out between 9th and 28th of February next year.