Even if you have never been interested in sustainability or climate change, you must have heard about the Paris Agreement, the most trending topic after Greta Thunberg ;)
We call the Paris Agreement to the international treaty adopted in December 2015 on the UNFCCC COP21 in Paris. I know you might be thinking "wait, what is UNFCCC? What is COP21?", we will get into that - I leave you the definitions and links to Wikipedia at the end of the article. As of now, you just need to remember that it is the treaty that poses the basis for climate change mitigation.
And why is the Paris Agreement so important for fighting climate change? Among others, the Paris Agreement set the global target to limit the climate warming "well below 2°C above pre-industrial levels and to pursue efforts to limit the temperature increase to 1.5°C". It was signed and ratified by +180 countries (representing almost 97% of global greenhouse gas (GHG) emissions). To accomplish that target, each country had to submit its intended nationally determined contribution (NDC), which is each country's commitment to reduce their GHG emissions after 2020. As an example, the United States (US) committed to achieve a 26-28% reduction over its 2005 emissions level in 2025, and to make best efforts to reduce its emissions by 28%. However, a year later president Donald Trump won the elections and announced the US would quit the Paris Agreement.
Leaving Trump aside, the Paris Agreement also set the basis for the voluntary cooperation among countries on the achievement of their NDCs. That is, an international carbon market where countries that have over-achieved their target can sell "excess" emissions reductions to other countries.
This is just the tip of the iceberg, if you want to learn more about the Paris Agreement I recommend you read its summary from UNFCCC page or the full Paris Agreement text. Also, if you have any question or a topic that would like me to write about, just add a comment below :)
Glossary of abbreviations:
UNFCCC: United Nations Framework Convention on Climate Change (https://en.wikipedia.org/wiki/United_Nations_Framework_Convention_on_Climate_Change)
COP21: Conference of the Parties #21 (https://en.wikipedia.org/wiki/2015_United_Nations_Climate_Change_Conference)