Water

Water is an inorganic compound with the chemical formula H₂O. It is a transparent, tasteless, odorless, and nearly colorless chemical substance. It is found everywhere on Earth, making up most of our streams, lakes, and oceans, as well as the fluids inside all living things. Because it can dissolve so many different substances, water is often called the "universal solvent."

On Earth, water can exist as a solid, a liquid, or a gas. We see it as rain, snow, fog, and steam, and it is constantly moving through the water cycle of evaporation, condensation, precipitation, and runoff. This movement helps shape our planet and supports all forms of life.

Water is also very important for our daily lives. Most of the fresh water that people use goes to agriculture, and many people depend on fishing in salt and fresh water for food. We also use water for cooling, heating, cooking, cleaning, and many enjoyable activities like swimming, surfing, ice skating, and skiing.

Etymology

The word water comes from Old English wæter, which is related to words in many other languages. For example, in Dutch it's water, in German it's Wasser, and in Russian it's вода́ (vodá). All these words share a common ancient root meaning 'water' or 'wet'.

History

Main articles: Origin of water on Earth § History of water on Earth, and Properties of water § History

Water has played an important role on our planet for a very long time. Scientists study how water first appeared on Earth and how it has changed over millions of years. They also look at the special properties of water that make it essential for life.

Properties

Main article: Properties of water

See also: Water (data page) and Water model

Water (H₂O) is a special kind of compound called an inorganic compound. At normal room temperature, it is a liquid that has no taste, no smell, and is almost clear, with just a tiny bit of blue color. It is very important because it can dissolve many other substances, which is why it is often called the “solvent of life.” Water can exist as a solid (ice), a liquid, and a gas (water vapor).

Water changes its state with temperature and pressure. When it gets cold, it freezes into ice. When it gets warm, it turns into vapor or steam. These changes are called phase transitions. One interesting fact about water is that it becomes less dense as it cools down, and it is less dense as a solid (ice) than as a liquid. This is why ice floats in water and why lakes don’t freeze solid in winter — the ice on top protects the water below.

On Earth

Water is found all around Earth, in oceans, lakes, rivers, and even in the air. Scientists study how water moves and changes through the planet. This includes learning about underground water, glaciers, and the oceans. All the water on Earth is called the hydrosphere, and there is a lot of it—about 1.386 billion cubic kilometers!

Water constantly moves through a process called the water cycle. It evaporates from oceans and plants release it into the air. Then, it falls back to Earth as rain, snow, or hail. This cycle helps shape our lands, creating valleys and rivers over time.

Water is very important for life and the environment. People use water for drinking and growing food. Most of Earth's fresh water is stored in glaciers, while some is underground or in lakes and rivers. Seawater makes up most of the ocean and has salts that change its freezing point. Tides—the rising and falling of ocean levels—are caused by the pull of the Moon and the Sun on Earth's waters.

Effects on life

Water is very important for all living things. It helps our bodies carry out many important processes, such as breaking down food for energy and building up our bodies. Without water, these processes could not happen.

Many animals and plants live in water. Fish breathe through gills, while animals like dolphins and whales need to come up for air. Plants like kelp and algae grow in the ocean, forming the base of many food chains. Water is where life first began, and it continues to support a huge variety of creatures.

Further information: Hydrobiology, Marine life, and Aquatic plant

Effects on human civilization

Civilization has historically flourished around rivers and major waterways. Ancient societies like Mesopotamia and Egypt depended on rivers such as the Tigris, Euphrates, and Nile for survival. Today, large cities like Rotterdam, London, New York City, and Tokyo owe their success in part to access to water for trade and transportation.

Water is essential for human health and daily life. It is used for drinking, cooking, cleaning, and many other purposes. Access to clean drinking water, known as drinking water or potable water, is crucial for preventing diseases. Unfortunately, more than 660 million people worldwide do not have access to safe drinking water. Water also plays a key role in agriculture, industry, and energy production, making it a vital resource for sustaining life and supporting economic activities.

Distribution in nature

Water is found all over the universe. It is made during the birth of stars, and huge clouds of water vapor have been found far away from Earth. We can also find water in the air around stars, planets, and moons.

On Earth, water is most often a liquid, covering most of our planet. It can also be found as ice on Earth, the Moon, Mars, and many other places in space. Water is very important for life as we know it.

Law, politics, and crisis

Water politics is the way water affects decisions and disagreements between countries and communities. Fresh water is very important and can cause conflicts because everyone needs it to live. Many places in the world still don’t have enough clean water or good ways to keep it clean.

Over the years, more people have gotten access to clean water, but millions still don’t have enough. Some experts think that by 2025, most of the world’s people will be affected by water problems. Good rules and careful planning are needed to make sure everyone has enough water and to protect rivers, lakes, and oceans.

In culture

Religion

See also: Sacred waters

Water is seen as a purifier in many religions. Faiths that use ritual washing include Christianity, Hinduism, Islam, Judaism, the Rastafari movement, Shinto, Taoism, and Wicca. In Christianity, immersion in water is a central part of the sacrament of baptism. In Islam, washing certain parts of the body with clean water is important before prayers. In Shinto, water is used in rituals to cleanse people or areas.

Philosophy

The Ancient Greek philosopher Empedocles saw water as one of the four basic elements of the universe. Thales believed that all things are made from water. In traditional Chinese philosophy, water is one of the five elements and is seen as a model for softness and strength.

Folklore

In many folktales, “living water” has magical powers, such as bringing the dead back to life. The idea of magical waters also appears in stories like the Fountain of Youth.

Art and activism

The modern novel Ulysses by James Joyce includes a famous passage called the “water hymn,” which celebrates the many qualities of water. Artists have also explored the importance of water through exhibitions and projects, highlighting its value to our lives.

Dihydrogen monoxide parody

Main article: Dihydrogen monoxide parody

Sometimes, water is called “dihydrogen monoxide” as a joke to mock people who don’t understand science. This name has been used in hoaxes to make people worry about water, which is actually safe and essential for life.

Music

The word “Water” is used by some Florida-based rappers as a catchphrase. Some have even made songs about the water in Florida.