This Saturday is Earth Day, and communities across the country are mobilizing to clean up their shared green spaces and waterways, plant air-cleaning trees and bring more attention to climate change.

This year’s Earth Day theme is “Invest in Our Planet.” EarthDay.org, which works with more than 150,000 partners in 192 countries, is inviting people to pledge online to take actions like growing more trees, supporting sustainable fashion, or helping end plastic pollution.

Earth Day is observed every year on April 22.

According to the Environmental Protection Agency, the first Earth Day was created in 1970 by Sen. Gaylord Nelson of Wisconsin as a way to force environmental protection issues onto the national agenda. Twenty million Americans demonstrated peacefully in support of the environment on that first Earth Day. By the end of that year, Congress authorized the creation of the EPA to tackle environmental issues. Since then, Congress has passed important regulatory legislation such as the Clean Air Act, the Water Quality Improvement Act and the Endangered Species Act.

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Earth Day became a global campaign in 1990, observed by 200 million people in 141 countries, according to EarthDay.org.

Earth Day is an opportunity to bring attention to the deteriorating state of the planet. The day is a reminder for people of all ages to reduce their usage of unsustainable products, that ending the use of pesticides can save threatened species, and clean water is an increasingly precious resource around the world. Earth Day’s expansion beyond the U.S. has also spurred efforts to decrease emissions internationally and keep the planet from warming beyond repair.

Today, Earth Day is most typically an opportunity for people to volunteer to clean up a beach or local park, help plant trees or make their way to a community event festival to learn more about helpful insects, composting or other green activities.

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But when individuals make small changes to live a more sustainable life – and not just on Earth Day – it can have a big impact. And the icing on the green cake is that a lot of these small acts also help save money.

The EPA has a list of tips that anyone can use to celebrate Earth Day everyday.