Eukaryotes are a type of organism whose cells have 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 eukaryotic cells to store and manage their genetic material more efficiently than prokaryotes, which lack a nucleus. Eukaryotic cells are generally larger and more complex than prokaryotic cells. They can be unicellular, like yeast, or multicellular, like humans. The complexity of eukaryotes enables them to perform various functions and adapt to different environments, making them a vital part of Earth's ecosystems.