Eukaryotic organisms are living beings whose cells contain a nucleus and other specialized structures called organelles. This group includes a wide variety of life forms, such as plants, animals, fungi, and protists. The presence of a nucleus allows these cells to store and manage their genetic material more efficiently, leading to greater complexity and diversity in their functions and forms. Unlike prokaryotic organisms, which are simpler and lack a nucleus, eukaryotic cells can form multicellular organisms. This complexity enables them to develop specialized tissues and organs, allowing for advanced processes like photosynthesis in plants and respiration in animals. Eukaryotes play crucial roles in ecosystems and are essential for life on Earth.