The most important invention of the last 100 years is the light bulb. Light bulbs change the world by allowing people to operate at night. According to historians, among those credited with creating incandescent lamps in the 1800s, Thomas Edison is credited as the main inventor because he created a perfect lighting system, including generators, wiring and carbon fiber light bulbs in 1879. Since then, people's sleep patterns have gradually changed. Instead of going to bed when it starts to get dark (because it's hard to do anything in the dark) and sleeping continuously until dawn, people now only spend about 7 to 8 hours sleeping.

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In my opinion, in the last 100 years, the most important invention is DNA. DNA is an acronym for deoxyribonucleic acid, it is made up of nucleotide units. DNA is an extremely important molecule for not only humans, but for most other organisms. DNA contains genetic material and genes - that's what makes us unique.A complete set of DNA contains 3 billion bases, 20,000 genes, and 23 pairs of chromosomes. We inherit half of our DNA from our father's sperm and half from our mother's eggs.DNA is pivotal to our growth, reproduction and health. It contains the instructions needed for cells to make proteins that affect many different processes and functions in the body. Because DNA is so important, damage or mutations can sometimes contribute to disease development. In fact, DNA is so fragile that it is estimated that tens of thousands of DNA-damaging events occur every day in each of our cells. This damage can be caused by errors in DNA replication, by free radicals, and by our exposure to UV radiation. But fortunately, our cells have specialized proteins that are able to detect and repair many cases of DNA damage.DNA contains the instructions necessary for an organism to grow, develop, and reproduce. These instructions are stored in sequences of nucleotide base pairs. The cells read the code at a time to make the proteins needed for growth. Each group of three bases corresponds to specific amino acids, which are the building blocks of proteins.