The definition of Chemistry has changed from time to time and was first coined by the scientist Robert Boyle and it meant as “Subject of material principles of mixed bodies” and then in 1730 its definition changed to “Art of resolving mixed, compound or aggregate bodies into their principles”, so on.
In today’s definition “Chemistry is the study of matter and energy and the interactions between them”. Both Chemistry and physics are a part of Science.
In Chemistry we focus on the properties of substances and their interactions between different types of matter, in particular those reactions that involve electrons. Whereas in Physics focus is more on the nuclear part of the atom.
Even Cooking is chemistry. When we study chemistry, we understand something about how things work. Chemistry isn't some secret knowledge, useless to anyone but a chemical scientist. It's the explanation for everyday things we tend to use, like a particular laundry detergent works better in hot water or why not all pain killers work equally on a headache. If you know something about chemistry, you can make educated preferance about everyday products that you use.
Chemistry importance in Human life
Chemistry is important because everything you do is chemistry! Even your body is made of chemicals. Chemistry can be used in most fields, but it's commonly seen in the fields of sciences and in medicine. Chemist’s, physicists, biologists, and students study chemistry. Doctors, nurses, dentists, pharmacists, physical therapists, and veterinarians all take chemistry courses. Even Science teachers study chemistry. Fire fighters learn about chemistry. So do truck drivers, plumbers, artists, hairdressers, chefs. It is a never ending list which is updated as usage of chemicals increase and its field increases.
A part of the importance of chemistry is in developing and testing medical treatments and medicines. Chemistry forms the heart of environmental issues as well. How would you distinguish which chemical is a nutrient and which one is a pollutant? How can you help in cleaning the environment? Which products can be used without harming the environment? Chemical reactions occur whenever we breathe, eat, or just sit there reading. It's important to understand chemistry if you are studying any Sciences. All sciences are interdependent and involve interactions with matter and its types.