By 1865, number of identified elements was 63 and with such a large number of elements it was very difficult to study individually the chemistry of all these elements and their innumerable compounds individually. To ease out this problem, scientists searched for a systematic way to organize their knowledge by classifying the elements. Here comes the basis of periodic table. Various elements have now been divided into different groups on the basis of similarities in chemical properties. This has made the study simpler as now the properties of elements are studied in groups rather than individually.