Chemistry can be defined as the study of matter, energy and the changes that accompanies matter and energy. Chemistry is the branch of science that deals with the identification of the substances of which matter is composed. Chemistry is the chemical composition and properties of a substance or body. Chemistry is the science of substances, or materials, their composition and characteristics, and the reactions which takes place between those substances. It is concerned with chemical elements in their pure state and when they are combined, that is, reactions of these elements and the compounds which they form. Origin of chemistry: Chemistry is a branch of science that has been around for a long time. In fact, chemistry is known to date back to as far as the prehistoric times. Due to the amount of time chemistry takes up on the timeline, the science is split into four general chronological categories. The four categories are: prehistoric times - beginning of the Christian era (black magic), beginning of the Christian era - end of 17th century (alchemy), end of 17th century - mid 19th century (traditional chemistry) and mid 19th century - present (modern chemistry). The Greek word "chemeia" first appears in about the fourth century and was used to designate the art of metal-working, especially the possible change of base metals into gold and silver. The Arabs later prefixed the article "al" and "alchemy" came finally to signify the arts of chemistry in general. "Chemeia" was probably derived from the Greek word chemi which means "black". There are three possible reasons for the use of this word: 1. The black soil of the Nile Valley gave the Greeks the name Chemi for Egypt where the chemical arts presumably originated. 2. A certain "blackening" process was frequently mentioned as a preliminary to whitening or yellowing of silver or gold. 3. In the sense of "dark" or "hidden", since the Dark, Hidden or Divine Art was the only name by which this science was known to the ancients. Some hold that the word chemistry had a Chinese origin. It may have been derived from the Hakka term KIM-MI or the Cantonese term KEM-MAI, which signifies "gone astray in search of gold" or "secret of gold". They are suggested to be the origin of the Greek "chemeia", the French "chimie", the German "Chemie", and the Arabian "alchemy". The term Chemistry originates from ancient Egyptian term khemeia. Khemeia was an Egyptian art which occurs in various Egyptian groups that was connected to mummification. Later along the history, its practices included things such as dyeing, metallurgy and glass making. Although the ancients knew of copper, silver, gold, tin, lead, iron, carbon and sulphur, they did not know that these are elements. To them, they follow the teachings of the 5th century BC Greek thinker and philosopher Empedocles and popularized by Aristotle. To them, matter was made up of four elements - the earth, air, fire and water. To them this classification made sense because after all, earth is not a solid, water is not a liquid, air not a gas and fire not an energy. Of course, to use people that study "Science" and call ourselves Scientists, that sentence does not make sense to us. When Greek thinking encountered the Egyptian art of khemeia, probably during Alexandria about 300 BC, alchemy was born and it flourished for two thousand years. Alchemy combined mysticism and much general scientific experimentation. The alchemists became obsessed with the search of immortality and trying to turn any kind of metals into gold. They were the first to make general use of many of the chemicals we use today, such as strong acids - sulphuric acid, hydrochloric acid and nitric acid. They also developed many experimental procedures such as filtration, dissolution of solids and simple distillation. The alchemists had built up a list of practical scientific information but they did not understand why things happened. Before our current understanding of chemistry, there are 3 more important concepts that were developed and followed: 1. Appreciation that scientific progress begins always with experiments and onservations 2. An understanding of what an element is - Robert Boyle and Antoine Lavoisier concluded the elements are the simplest unit that cannot be further broken down. 3. Development of the Atomic Theory - Greek philosopher Leucippus and Democritus proposed about this theory but was not successful. John Dalton is the one that came in to prove its existence. And with that, the Russian Dmitri Mendeleev (1834 - 1907) came in to construct the world famous The Periodic Table which are recognised as the most important system of classification in Chemistry. 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