OK, let's start at the beginning: what exactly is a forest? Simply put, a forest is an area of land that's dominated by trees and undergrowth vegetation. But forests are also so much more than trees: depending on the type of forest and where in the world they are, they can have clear rivers to swim in, big rocks to climb, bright wildflowers to sniff, and more!

While all forests are primarily composed of trees, the Amazon Rainforest and the Russian Tiaga look very different. As a rule of thumb, there are three main types of forests: rainforests, temperate forests and boreal forests — with subcategories almost as diverse as the species that call them home.

Everything that lives in a forest makes up its ecosystem, and the wide range of biodiversity found in these ecosystems is truly astounding. In fact, more than 80% of the plants, animals and insects living on land can be found in the world's forests! The world's biodiversity needs our help protecting its home.

Before people began cutting down forests to build cities and create farmland, forests covered about half the Earth's land area. Despite how important they are, forests continue to be chopped down at an alarming rate, causing many to worry about the state of the world's forests ow and in the future. 

Humans evolved with trees and have relied on them for shade, shelter, food and medicine for generations, but today's natural spaces look very different from the massive swaths of primary forest that early humans knew. Due to population growth, the industrial revolution and more, the pace of deforestation has snowballed into what we see today. 

What do paper, cinnamon, lumber, maple syrup, rubber and medicine have in common? They all come from trees! That's because trees come in all shapes and sizes and many tree species provide important resources for humans. When sustainably harvested, these resources can provide a steady income for people who create and sell forest products. 

From roots spreading deep underground to wood mushrooms growing high up above, forests are filled with medicine that can help with many of the things that ail humankind. Those who live in close connection with the forest know what plant to grab to stop bleeding, ease a headache, draw out a bee sting, disinfect wounds and more!

From clean water to clean air, to forest bathing, forests are crucial for the planet and for our well-being. That's because trees use their leaves to filter air pollution, absorb and slowly release rainwater, produce powerful chemicals and positive ions that help us release stress and anxiety, absorb carbon and release oxygen and more!

Deforestation, or the act of cutting down forest to make room for other land uses, is a growing problem. So many forests are being cut down that it's making the planet sick and posing a danger to life on earth. Fewer trees also means less rainfall and more drought — and many animals and plants face extinction as their forest homes are destroyed.

Cutting down trees releases all the carbon dioxide they once stored. Carbon dioxide is a greenhouse gas which traps heat from the Sun close to Earth's surface, causing global temperatures to rise and bringing about the process we know as climate change. Trees absorb carbon and use it to grow their trunks, branches and roots, making them living carbon sinks!

Forests are often cleared to make room for people's homes as cities expand to accommodate the world's growing population. Trees are also cut so farmers can grow more food and raise livestock like cows, pigs, and sheep. They're also logged to make the products we all enjoy like furniture, paper, and lumber to build houses.