Everything is made of matter and chemistry is the study of matter. The basic building blocks of all matter are elements. Some elements are hydrogen and sodium. You can learn more about chemistry here.
The periodic table helps chemists, people who study matter, learn and discover new things. It helps chemists discover new elements, because the table helps observe connections between elements, leading chemists to discover elements they have never known about before. The periodic table also helps chemists determining which elements combine easily. The periodic table has become one of the most useful tools for chemists.
Before many elements were discovered, the philosopher Aristotle believed that all matter on earth was made of only four elements; water, earth, air, and fire. People believed this was true for almost 2,000 years. In 1661, though, Robert Boyle said that there had to be more than four elements. This became true and by 2011 more than 118 elements were discovered.
The reason why all of this is important is because without an understanding of the periodic table, many products, medicines, plastics, food flavorings, and more wouldn’t exist.
You can learn more about the periodic table by reading the book The Elements which can be found here: