🚰 Water is a chemical substance composed of two hydrogen atoms bonded to one oxygen atom, with the molecular formula H₂O. It is one of the most vital compounds on Earth, making up about 71% of the planet’s surface. Water exists in three primary states—liquid, gas (vapor), and solid (ice)—depending on temperature and pressure. As a liquid, it is essential for life, supporting the biochemical processes in organisms, regulating temperature through heat absorption and release, and acting as a solve

With so many symptoms in common, it can be hard to tell the difference between a cold and the flu. But these two illnesses are caused by different viruses, and there are some differences in how they present. Here’s how to tell which is which. | Cleveland Clinic