Cloud condensation nuclei (CCN) are tiny particles present in the atmosphere that serve as the nuclei for the condensation of water vapor to form cloud droplets. These particles can be natural (such as sea salt, dust, or pollen) or anthropogenic (such as pollution from vehicle emissions). CCN are important for cloud formation and precipitation processes, as they affect the properties and development of clouds. Research in this area focuses on understanding the sources, characteristics, and properties of CCN, as well as their impact on cloud formation, cloud properties, and climate. Scientists study how different types of CCN influence cloud development, cloud droplet size distribution, and cloud albedo, which can have implications for weather patterns, precipitation, and climate change. Studying CCN is crucial for improving our understanding of cloud processes and their role in the Earth's climate system.