How important is the periodic table? It is very important - it provides chemists with basic information about each element, like atomic number and weight. As you study chemistry further, you will find out that each element’s position on the table gives important hints to its chemical and physical properties. The very shape of the periodic table actually provides quite a bit of information about the elements' behavior.
Just like any collection that one has, there is an inclination to try to categorize that collection into a logical system. When Dmitri Mendeleev created his periodic table in 1869, there were only 63 elements. His monumental table accommodated each of those, and most incredibly, left room for many elements yet to be discovered. Thanks, Dmitri!